diff --git a/pyrobolearn/algos/updater.py b/pyrobolearn/algos/updater.py
index b4e1d06..dbad108 100644
--- a/pyrobolearn/algos/updater.py
+++ b/pyrobolearn/algos/updater.py
@@ -232,7 +232,7 @@ class Updater(object):
             raise TypeError("Expecting the given ticks to be a dictionary, instead got: {}".format(type(ticks)))
 
         # check first the items already present in the ticks
-        for key, value in ticks.iteritems():
+        for key, value in ticks.items():
             # check that the key is a Loss or ParamaterUpdater
             if not isinstance(key, (Loss, ParameterUpdater)):
                 raise TypeError("Expecting the given key for the tick to be an instance of `Loss` or "
diff --git a/pyrobolearn/storages/er.py b/pyrobolearn/storages/er.py
index 0a112cb..b67d42c 100644
--- a/pyrobolearn/storages/er.py
+++ b/pyrobolearn/storages/er.py
@@ -380,7 +380,7 @@ class ExperienceReplay(DictStorage):  # ExperienceReplayStorage(DictStorage):
         batch = {}
 
         # go through each attribute in the  and sample from the tensors
-        for key, value in self.iteritems():
+        for key, value in self.items():
             if isinstance(value, list):  # value = list of tensors
                 batch[key] = [val[indices] for val in value]
             else:  # value = tensor
diff --git a/pyrobolearn/storages/storage.py b/pyrobolearn/storages/storage.py
index f7ffbed..1722594 100644
--- a/pyrobolearn/storages/storage.py
+++ b/pyrobolearn/storages/storage.py
@@ -686,7 +686,7 @@ class Batch(DictStorage):
 
             # print other variables
             tmp = {'states', 'actions', 'rewards', 'masks', 'returns'}
-            for key, value in kwargs.iteritems():
+            for key, value in kwargs.items():
                 if key not in tmp:
                     print("{}: {}".format(key, value))
 
@@ -1166,7 +1166,7 @@ class RolloutStorage(DictStorage):  # TODO: think about when multiple policies:
         #     print("Indices: {}".format(indices))
 
         # go through each attribute and sample from the tensors
-        for key, value in self.iteritems():
+        for key, value in self.items():
             # print("batch - add key: {}".format(key))
             if isinstance(value, list):  # value = list of tensors
                 batch[key] = [sample(val, indices) for val in value]  # [[I, *shape] for each shape]
diff --git a/pyrobolearn/worlds/world.py b/pyrobolearn/worlds/world.py
index 0ab556f..0dc2982 100644
--- a/pyrobolearn/worlds/world.py
+++ b/pyrobolearn/worlds/world.py
@@ -269,7 +269,7 @@ class World(object):
         world = self.__class__(simulator=simulator, gravity=gravity)
 
         # load bodies in world
-        for id_, items in self.ids.iteritems():
+        for id_, items in self.ids.items():
             if not isinstance(items, list):
                 items = [items]
             for item in items: