Primary, isolated deep venous incompetence is rare, difficult to diagnose, and can lead to the development of venous stasis ulcers. We herein report a case demonstrating chronic venous stasis ulcers due to primary, isolated deep venous incompetence, which was misdiagnosed as vasculitis ulcers associated with systemic lupus erythematosus (SLE). Although primary, isolated deep venous incompetence is rare, it is important to bear this possibility in mind when a patient presents with leg ulcers.