diff --git a/doc/en/usage.rst b/doc/en/usage.rst
index 08c158aac..a3d56deff 100644
--- a/doc/en/usage.rst
+++ b/doc/en/usage.rst
@@ -74,6 +74,14 @@ Examples for modifying traceback printing::
     py.test --tb=native  # Python standard library formatting
     py.test --tb=no      # no traceback at all
 
+The ``--full-trace`` causes very long traces to be printed on error (longer
+than ``--tb=long``). It also ensures that a stack trace is printed on
+**KeyboardInterrrupt** (Ctrl+C).
+This is very useful if the tests are taking too long and you interrupt them
+with Ctrl+C to find out where the tests are *hanging*. By default no output
+will be shown (because KeyboardInterrupt is catched by pytest). By using this
+option you make sure a trace is shown.
+
 Dropping to PDB_ (Python Debugger) on failures
 -----------------------------------------------