The association between Systemic Lupus Erythematosus (SLE) and thymoma occurs with a greater frequency than dictated by coincidence alone. The immunologic effects of thymectomy on the appearance and/or the course of SLE are still to be elucidated. We report one case of SLE diagnosed at the same time as thymoma, and two cases of thymoma associated with immunologic disorders in the absence of clinical signs and symptoms diagnostic of SLE.