--- src/org/python/core/PySystemState.java
+++ src/org/python/core/PySystemState.java
@@ -646,6 +646,12 @@
             if (jythonpath != null) {
                 registry.setProperty("python.path", jythonpath);
             }
+            else {
+                jythonpath = System.getenv("PYTHONPATH");
+                if (jythonpath != null) {
+                    registry.setProperty("python.path", jythonpath);
+                }
+            }
         } catch (SecurityException e) {
         }
         registry.putAll(postProperties);