diff --git a/doc/requirements.txt b/doc/requirements.txt
index 1a8dfb8e9a..89510877e1 100644
--- a/doc/requirements.txt
+++ b/doc/requirements.txt
@@ -6,7 +6,6 @@ hacking>=3.0 # Apache-2.0
 os-api-ref>=1.4.0 # Apache-2.0
 sphinxcontrib-actdiag>=0.8.5 # BSD
 sphinxcontrib-apidoc>=0.2.1 # BSD
-sphinxcontrib-blockdiag>=1.5.4 # BSD
 sphinxcontrib-nwdiag>=0.9.5 # BSD
 sphinxcontrib-seqdiag>=0.8.4 # BSD
 docutils>=0.11 # OSI-Approved Open Source, Public Domain
diff --git a/doc/source/conf.py b/doc/source/conf.py
index 2ae73c1c94..ae393be03e 100644
--- a/doc/source/conf.py
+++ b/doc/source/conf.py
@@ -57,7 +57,6 @@ extensions = [
     'sphinx.ext.autodoc',
     'sphinx.ext.todo',
     'sphinx.ext.viewcode',
-    'sphinxcontrib.blockdiag',
     'sphinxcontrib.actdiag',
     'sphinxcontrib.seqdiag',
     'sphinxcontrib.nwdiag',
diff --git a/specs-tests/test_titles.py b/specs-tests/test_titles.py
index f33bd02a08..2a106463a9 100644
--- a/specs-tests/test_titles.py
+++ b/specs-tests/test_titles.py
@@ -32,7 +32,6 @@ def fake_role(name, rawtext, text, lineno, inliner,
 
 
 directives.register_directive('seqdiag', FakeDirective)
-directives.register_directive('blockdiag', FakeDirective)
 directives.register_directive('nwdiag', FakeDirective)
 directives.register_directive('actdiag', FakeDirective)
 directives.register_directive('graphviz', FakeDirective)
diff --git a/specs/template.rst b/specs/template.rst
index 64a26211c3..b30fab87dc 100644
--- a/specs/template.rst
+++ b/specs/template.rst
@@ -35,7 +35,7 @@ Some notes about using this template:
 
 * If you would like to provide a diagram with your spec, text representations
   are preferred. http://asciiflow.com/ is a very nice tool to assist with
-  making ascii diagrams. blockdiag is another tool. These are described below.
+  making ascii diagrams. These are described below.
   For more complicated diagrams that need "real" graphics, yet still should
   be in the git revision control system, GraphViz .dot files are acceptable.
   If you require an image (screenshot) for your BP, attaching that to the BP
@@ -51,14 +51,6 @@ asciiflow::
   |          +-----+           +--------+          |
   +----------+     +-----------+        +----------+
 
-blockdiag
-
-.. blockdiag::
-
-  blockdiag sample {
-    a -> b -> c;
-  }
-
 actdiag
 
 .. actdiag::