diff --git a/doc/ext/docscrape.py b/doc/ext/docscrape.py
index ad5998cc..b90b49c8 100644
--- a/doc/ext/docscrape.py
+++ b/doc/ext/docscrape.py
@@ -9,6 +9,7 @@ import pydoc
 from StringIO import StringIO
 from warnings import warn
 
+
 class Reader(object):
     """A line-based string reader.
 
@@ -369,7 +370,7 @@ class NumpyDocString(object):
         idx = self['index']
         out = []
         out += ['.. index:: %s' % idx.get('default','')]
-        for section, references in idx.iteritems():
+        for section, references in idx.items():
             if section == 'default':
                 continue
             out += ['   :%s: %s' % (section, ', '.join(references))]
diff --git a/doc/ext/docscrape_sphinx.py b/doc/ext/docscrape_sphinx.py
index 9f4350d4..9e66c4be 100644
--- a/doc/ext/docscrape_sphinx.py
+++ b/doc/ext/docscrape_sphinx.py
@@ -2,6 +2,7 @@ import re, inspect, textwrap, pydoc
 import sphinx
 from docscrape import NumpyDocString, FunctionDoc, ClassDoc
 
+
 class SphinxDocString(NumpyDocString):
     def __init__(self, docstring, config={}):
         self.use_plots = config.get('use_plots', False)
@@ -127,7 +128,7 @@ class SphinxDocString(NumpyDocString):
             return out
 
         out += ['.. index:: %s' % idx.get('default','')]
-        for section, references in idx.iteritems():
+        for section, references in idx.items():
             if section == 'default':
                 continue
             elif section == 'refguide':
diff --git a/doc/ext/plot_directive.py b/doc/ext/plot_directive.py
index dc86552b..4a32b6f1 100644
--- a/doc/ext/plot_directive.py
+++ b/doc/ext/plot_directive.py
@@ -132,6 +132,7 @@ except ImportError:
     def format_template(template, **kw):
         return jinja.from_string(template, **kw)
 
+
 import matplotlib
 import matplotlib.cbook as cbook
 matplotlib.use('Agg')
@@ -234,7 +235,7 @@ def mark_plot_labels(app, document):
     the "htmlonly" (or "latexonly") node to the actual figure node
     itself.
     """
-    for name, explicit in document.nametypes.iteritems():
+    for name, explicit in document.nametypes.items():
         if not explicit:
             continue
         labelid = document.nameids[name]
diff --git a/doc/logo/scikit_image_logo.py b/doc/logo/scikit_image_logo.py
index 014c5786..85ba5199 100644
--- a/doc/logo/scikit_image_logo.py
+++ b/doc/logo/scikit_image_logo.py
@@ -24,7 +24,6 @@ from skimage.filter import sobel
 
 import scipy_logo
 
-
 # Utility functions
 # =================
 
@@ -49,7 +48,7 @@ def prepare_axes(ax):
     plt.sca(ax)
     ax.xaxis.set_visible(False)
     ax.yaxis.set_visible(False)
-    for spine in ax.spines.itervalues():
+    for spine in ax.spines.values():
         spine.set_visible(False)
 
 
diff --git a/skimage/io/_io.py b/skimage/io/_io.py
index 5dfe107b..7b21b2b8 100644
--- a/skimage/io/_io.py
+++ b/skimage/io/_io.py
@@ -1,9 +1,13 @@
 __all__ = ['Image', 'imread', 'imread_collection', 'imsave', 'imshow', 'show',
            'push', 'pop']
 
+try:
+    from urllib.request import urlopen
+except ImportError:
+    from urllib2 import urlopen
+
 import os
 import re
-import urllib2
 import tempfile
 from io import BytesIO
 
@@ -132,7 +136,7 @@ def imread(fname, as_grey=False, plugin=None, flatten=None,
     if is_url(fname):
         _, ext = os.path.splitext(fname)
         with tempfile.NamedTemporaryFile(delete=False, suffix=ext) as f:
-            u = urllib2.urlopen(fname)
+            u = urlopen(fname)
             f.write(u.read())
         img = call_plugin('imread', f.name, plugin=plugin, **plugin_args)
         os.remove(f.name)
diff --git a/skimage/io/_plugins/plugin.py b/skimage/io/_plugins/plugin.py
index 7c25fb4e..5e04f320 100644
--- a/skimage/io/_plugins/plugin.py
+++ b/skimage/io/_plugins/plugin.py
@@ -12,6 +12,7 @@ except ImportError:
 import os.path
 from glob import glob
 
+
 plugin_store = None
 
 plugin_provides = {}
@@ -174,7 +175,7 @@ def available(loaded=False):
 
     """
     active_plugins = set()
-    for plugin_func in plugin_store.itervalues():
+    for plugin_func in plugin_store.values():
         for plugin, func in plugin_func:
             active_plugins.add(plugin)
 
diff --git a/skimage/viewer/__init__.py b/skimage/viewer/__init__.py
index e3681339..5eed9589 100644
--- a/skimage/viewer/__init__.py
+++ b/skimage/viewer/__init__.py
@@ -1 +1 @@
-from viewers import ImageViewer, CollectionViewer
+from .viewers import ImageViewer, CollectionViewer
diff --git a/skimage/viewer/plugins/base.py b/skimage/viewer/plugins/base.py
index aa6b585a..2d8c7175 100644
--- a/skimage/viewer/plugins/base.py
+++ b/skimage/viewer/plugins/base.py
@@ -153,7 +153,7 @@ class Plugin(QtGui.QDialog):
             return
         arguments = [self._get_value(a) for a in self.arguments]
         kwargs = dict([(name, self._get_value(a))
-                       for name, a in self.keyword_arguments.iteritems()])
+                       for name, a in self.keyword_arguments.items()])
         filtered = self.image_filter(*arguments, **kwargs)
         self.display_filtered_image(filtered)
 
diff --git a/skimage/viewer/utils/core.py b/skimage/viewer/utils/core.py
index 0b97d8c3..e4985a9e 100644
--- a/skimage/viewer/utils/core.py
+++ b/skimage/viewer/utils/core.py
@@ -81,7 +81,7 @@ class LinearColormap(LinearSegmentedColormap):
     """
     def __init__(self, name, segmented_data, **kwargs):
         segmented_data = dict((key, [(x, y, y) for x, y in value])
-                              for key, value in segmented_data.iteritems())
+                              for key, value in segmented_data.items())
         LinearSegmentedColormap.__init__(self, name, segmented_data, **kwargs)