diff --git a/implementations/onblocks/datanodestore/DataLeafNode.cpp b/implementations/onblocks/datanodestore/DataLeafNode.cpp
index 3df4b546..6f9b6b4e 100644
--- a/implementations/onblocks/datanodestore/DataLeafNode.cpp
+++ b/implementations/onblocks/datanodestore/DataLeafNode.cpp
@@ -11,6 +11,8 @@ namespace blobstore {
 namespace onblocks {
 namespace datanodestore {
 
+constexpr uint32_t DataLeafNode::MAX_STORED_BYTES;
+
 DataLeafNode::DataLeafNode(DataNodeView view)
 : DataNode(std::move(view)) {
   assert(*node().Depth() == 0);
diff --git a/implementations/onblocks/datatreestore/DataTree.cpp b/implementations/onblocks/datatreestore/DataTree.cpp
index 621b4fea..1dc158e0 100644
--- a/implementations/onblocks/datatreestore/DataTree.cpp
+++ b/implementations/onblocks/datatreestore/DataTree.cpp
@@ -7,6 +7,7 @@
 #include "impl/algorithms.h"
 
 #include "messmer/cpp-utils/pointer.h"
+#include <cmath>
 
 using blockstore::Key;
 using blobstore::onblocks::datanodestore::DataNodeStore;
@@ -102,6 +103,57 @@ unique_ptr<DataNode> DataTree::releaseRootNode() {
   return std::move(_rootNode);
 }
 
+void DataTree::traverseLeaves(uint32_t beginIndex, uint32_t endIndex, function<void (DataLeafNode*, uint32_t)> func) {
+  assert(beginIndex <= endIndex);
+  //TODO assert(beginIndex <= numLeaves());
+  //TODO assert(endIndex <= numLeaves());
+  traverseLeaves(_rootNode.get(), 0, beginIndex, endIndex, func);
+}
+
+//TODO Put intPow, ceilDivision, maxZeroSubtraction into utils and write test cases
+
+uint32_t intPow(uint32_t base, uint32_t exponent) {
+  uint32_t result = 1;
+  for(int i = 0; i < exponent; ++i) {
+    result *= base;
+  }
+  return result;
+}
+
+uint32_t ceilDivision(uint32_t dividend, uint32_t divisor) {
+  return (dividend + divisor - 1)/divisor;
+}
+
+uint32_t maxZeroSubtraction(uint32_t minuend, uint32_t subtrahend) {
+  if (minuend < subtrahend) {
+    return 0u;
+  }
+  return minuend-subtrahend;
+}
+
+void DataTree::traverseLeaves(DataNode *root, uint32_t leafOffset, uint32_t beginIndex, uint32_t endIndex, function<void (DataLeafNode*, uint32_t)> func) {
+  DataLeafNode *leaf = dynamic_cast<DataLeafNode*>(root);
+  if (leaf != nullptr) {
+    assert(beginIndex <= 1 && endIndex <= 1);
+    if (beginIndex == 0 && endIndex == 1) {
+      func(leaf, leafOffset);
+    }
+    return;
+  }
+
+  DataInnerNode *inner = dynamic_cast<DataInnerNode*>(root);
+  uint32_t leavesPerChild = intPow(DataInnerNode::MAX_STORED_CHILDREN, root->depth()-1);
+  uint32_t beginChild = beginIndex/leavesPerChild;
+  uint32_t endChild = ceilDivision(endIndex, leavesPerChild);
+
+  for (uint32_t childIndex = beginChild; childIndex < endChild; ++childIndex) {
+    uint32_t childOffset = childIndex * leavesPerChild;
+    uint32_t localBeginIndex = maxZeroSubtraction(beginIndex, childOffset);
+    uint32_t localEndIndex = std::min(leavesPerChild, endIndex - childOffset);
+    auto child = _nodeStore->load(inner->getChild(childIndex)->key());
+    traverseLeaves(child.get(), leafOffset + childOffset, localBeginIndex, localEndIndex, func);
+  }
+}
 
 }
 }
diff --git a/implementations/onblocks/datatreestore/DataTree.h b/implementations/onblocks/datatreestore/DataTree.h
index 52245429..92a255e8 100644
--- a/implementations/onblocks/datatreestore/DataTree.h
+++ b/implementations/onblocks/datatreestore/DataTree.h
@@ -31,6 +31,8 @@ public:
 
   void flush() const;
 
+  void traverseLeaves(uint32_t beginIndex, uint32_t endIndex, std::function<void (datanodestore::DataLeafNode*, uint32_t)> func);
+
 private:
   datanodestore::DataNodeStore *_nodeStore;
   std::unique_ptr<datanodestore::DataNode> _rootNode;
@@ -45,6 +47,8 @@ private:
   void deleteLastChildSubtree(datanodestore::DataInnerNode *node);
   void ifRootHasOnlyOneChildReplaceRootWithItsChild();
 
+  void traverseLeaves(datanodestore::DataNode *root, uint32_t leafOffset, uint32_t beginIndex, uint32_t endIndex, std::function<void (datanodestore::DataLeafNode*, uint32_t)> func);
+
   DISALLOW_COPY_AND_ASSIGN(DataTree);
 };
 
diff --git a/test/implementations/onblocks/datatreestore/traverseLeaves/DataTreeTest_TraverseLeaves.cpp b/test/implementations/onblocks/datatreestore/traverseLeaves/DataTreeTest_TraverseLeaves.cpp
new file mode 100644
index 00000000..2c8cdea3
--- /dev/null
+++ b/test/implementations/onblocks/datatreestore/traverseLeaves/DataTreeTest_TraverseLeaves.cpp
@@ -0,0 +1,190 @@
+#include "../testutils/DataTreeTest.h"
+#include <google/gmock/gmock.h>
+
+using ::testing::_;
+
+using blobstore::onblocks::datanodestore::DataLeafNode;
+using blobstore::onblocks::datanodestore::DataInnerNode;
+using blobstore::onblocks::datanodestore::DataNode;
+using blobstore::onblocks::datatreestore::DataTree;
+using blockstore::Key;
+
+class TraversorMock {
+public:
+  MOCK_METHOD2(called, void(DataLeafNode*, uint32_t));
+};
+
+MATCHER_P(KeyEq, expected, "node key equals") {
+  return arg->key() == expected;
+}
+
+class DataTreeTest_TraverseLeaves: public DataTreeTest {
+public:
+  void TraverseLeaves(DataNode *root, uint32_t beginIndex, uint32_t endIndex) {
+    root->flush();
+    auto tree = treeStore.load(root->key());
+    tree->traverseLeaves(beginIndex, endIndex, [this] (DataLeafNode *leaf, uint32_t nodeIndex) {
+      traversor.called(leaf, nodeIndex);
+    });
+  }
+  TraversorMock traversor;
+};
+
+TEST_F(DataTreeTest_TraverseLeaves, TraverseSingleLeafTree) {
+  auto root = CreateLeaf();
+  EXPECT_CALL(traversor, called(KeyEq(root->key()), 0)).Times(1);
+
+  TraverseLeaves(root.get(), 0, 1);
+}
+
+TEST_F(DataTreeTest_TraverseLeaves, TraverseNothingInSingleLeafTree1) {
+  auto root = CreateLeaf();
+  EXPECT_CALL(traversor, called(_, _)).Times(0);
+
+  TraverseLeaves(root.get(), 0, 0);
+}
+
+TEST_F(DataTreeTest_TraverseLeaves, TraverseNothingInSingleLeafTree2) {
+  auto root = CreateLeaf();
+  EXPECT_CALL(traversor, called(_, _)).Times(0);
+
+  TraverseLeaves(root.get(), 1, 1);
+}
+
+TEST_F(DataTreeTest_TraverseLeaves, TraverseFirstLeafOfFullTwolevelTree) {
+  auto root = CreateFullTwoLevel();
+  auto firstleafkey = root->getChild(0)->key();
+  EXPECT_CALL(traversor, called(KeyEq(firstleafkey), 0)).Times(1);
+
+  TraverseLeaves(root.get(), 0, 1);
+}
+
+TEST_F(DataTreeTest_TraverseLeaves, TraverseMiddleLeafOfFullTwolevelTree) {
+  auto root = CreateFullTwoLevel();
+  auto leafkey = root->getChild(5)->key();
+  EXPECT_CALL(traversor, called(KeyEq(leafkey), 5)).Times(1);
+
+  TraverseLeaves(root.get(), 5, 6);
+}
+
+TEST_F(DataTreeTest_TraverseLeaves, TraverseLastLeafOfFullTwolevelTree) {
+  auto root = CreateFullTwoLevel();
+  auto leafkey = root->getChild(DataInnerNode::MAX_STORED_CHILDREN-1)->key();
+  EXPECT_CALL(traversor, called(KeyEq(leafkey), DataInnerNode::MAX_STORED_CHILDREN-1)).Times(1);
+
+  TraverseLeaves(root.get(), DataInnerNode::MAX_STORED_CHILDREN-1, DataInnerNode::MAX_STORED_CHILDREN);
+}
+
+TEST_F(DataTreeTest_TraverseLeaves, TraverseNothingInFullTwolevelTree1) {
+  auto root = CreateFullTwoLevel();
+  EXPECT_CALL(traversor, called(_, _)).Times(0);
+
+  TraverseLeaves(root.get(), 0, 0);
+}
+
+TEST_F(DataTreeTest_TraverseLeaves, TraverseNothingInFullTwolevelTree2) {
+  auto root = CreateFullTwoLevel();
+  EXPECT_CALL(traversor,called(_, _)).Times(0);
+
+  TraverseLeaves(root.get(), DataInnerNode::MAX_STORED_CHILDREN, DataInnerNode::MAX_STORED_CHILDREN);
+}
+
+TEST_F(DataTreeTest_TraverseLeaves, TraverseFirstLeafOfThreeLevelMinDataTree) {
+  auto root = CreateThreeLevelMinData();
+  auto firstleafkey = LoadInnerNode(root->getChild(0)->key())->getChild(0)->key();
+  EXPECT_CALL(traversor, called(KeyEq(firstleafkey), 0)).Times(1);
+
+  TraverseLeaves(root.get(), 0, 1);
+}
+
+TEST_F(DataTreeTest_TraverseLeaves, TraverseMiddleLeafOfThreeLevelMinDataTree) {
+  auto root = CreateThreeLevelMinData();
+  auto leafkey = LoadInnerNode(root->getChild(0)->key())->getChild(5)->key();
+  EXPECT_CALL(traversor, called(KeyEq(leafkey), 5)).Times(1);
+
+  TraverseLeaves(root.get(), 5, 6);
+}
+
+TEST_F(DataTreeTest_TraverseLeaves, TraverseLastLeafOfThreeLevelMinDataTree) {
+  auto root = CreateThreeLevelMinData();
+  auto leafkey = LoadInnerNode(root->getChild(1)->key())->getChild(0)->key();
+  EXPECT_CALL(traversor, called(KeyEq(leafkey), DataInnerNode::MAX_STORED_CHILDREN)).Times(1);
+
+  TraverseLeaves(root.get(), DataInnerNode::MAX_STORED_CHILDREN, DataInnerNode::MAX_STORED_CHILDREN+1);
+}
+
+TEST_F(DataTreeTest_TraverseLeaves, TraverseAllLeavesOfFullTwolevelTree) {
+  auto root = CreateFullTwoLevel();
+  for (int i = 0; i < DataInnerNode::MAX_STORED_CHILDREN; ++i) {
+    auto leafkey = root->getChild(i)->key();
+    EXPECT_CALL(traversor, called(KeyEq(leafkey), i)).Times(1);
+  }
+
+  TraverseLeaves(root.get(), 0, DataInnerNode::MAX_STORED_CHILDREN);
+}
+
+TEST_F(DataTreeTest_TraverseLeaves, TraverseAllLeavesOfThreelevelMinDataTree) {
+  auto root = CreateThreeLevelMinData();
+  auto node = LoadInnerNode(root->getChild(0)->key());
+  for (int i = 0; i < DataInnerNode::MAX_STORED_CHILDREN; ++i) {
+    auto leafkey = node->getChild(i)->key();
+    EXPECT_CALL(traversor, called(KeyEq(leafkey), i)).Times(1);
+  }
+  Key lastleafkey = LoadInnerNode(root->getChild(1)->key())->getChild(0)->key();
+  EXPECT_CALL(traversor, called(KeyEq(lastleafkey), DataInnerNode::MAX_STORED_CHILDREN)).Times(1);
+
+  TraverseLeaves(root.get(), 0, DataInnerNode::MAX_STORED_CHILDREN+1);
+}
+
+TEST_F(DataTreeTest_TraverseLeaves, TraverseFirstChildOfThreelevelMinDataTree) {
+  auto root = CreateThreeLevelMinData();
+  auto node = LoadInnerNode(root->getChild(0)->key());
+  for (int i = 0; i < DataInnerNode::MAX_STORED_CHILDREN; ++i) {
+    auto leafkey = node->getChild(i)->key();
+    EXPECT_CALL(traversor, called(KeyEq(leafkey), i)).Times(1);
+  }
+
+  TraverseLeaves(root.get(), 0, DataInnerNode::MAX_STORED_CHILDREN);
+}
+
+TEST_F(DataTreeTest_TraverseLeaves, TraverseFirstPartOfThreelevelMinDataTree) {
+  auto root = CreateThreeLevelMinData();
+  auto node = LoadInnerNode(root->getChild(0)->key());
+  for (int i = 0; i < 5; ++i) {
+    auto leafkey = node->getChild(i)->key();
+    EXPECT_CALL(traversor, called(KeyEq(leafkey), i)).Times(1);
+  }
+
+  TraverseLeaves(root.get(), 0, 5);
+}
+
+TEST_F(DataTreeTest_TraverseLeaves, TraverseInnerPartOfThreelevelMinDataTree) {
+  auto root = CreateThreeLevelMinData();
+  auto node = LoadInnerNode(root->getChild(0)->key());
+  for (int i = 5; i < 10; ++i) {
+    auto leafkey = node->getChild(i)->key();
+    EXPECT_CALL(traversor, called(KeyEq(leafkey), i)).Times(1);
+  }
+
+  TraverseLeaves(root.get(), 5, 10);
+}
+
+TEST_F(DataTreeTest_TraverseLeaves, TraverseLastPartOfThreelevelMinDataTree) {
+  auto root = CreateThreeLevelMinData();
+  auto node = LoadInnerNode(root->getChild(0)->key());
+  for (int i = 5; i < DataInnerNode::MAX_STORED_CHILDREN; ++i) {
+    auto leafkey = node->getChild(i)->key();
+    EXPECT_CALL(traversor, called(KeyEq(leafkey), i)).Times(1);
+  }
+  Key lastleafkey = LoadInnerNode(root->getChild(1)->key())->getChild(0)->key();
+  EXPECT_CALL(traversor, called(KeyEq(lastleafkey), DataInnerNode::MAX_STORED_CHILDREN)).Times(1);
+
+  TraverseLeaves(root.get(), 5, DataInnerNode::MAX_STORED_CHILDREN+1);
+}
+
+//TODO First/Inner/LastPart of FullTwoLevelTree
+//TODO Test cases with a larger threelevel tree (say 5 children being full twolevel trees)
+//TODO Some few testcases with full threelevel tree
+//TODO Some few testcases with fourlevel mindata tree
+
+//TODO ...more test cases?