The occurrence of myasthenia gravis (MG) with systemic lupus erythematosus (SLE) seems to be more common than random association alone would predict. Moreover, both share immunologic aspects, tissue-directed antibodies and T and B cell abnormalities. To our knowledge, 7 cases of MG in association with SLE have been reported in the English literature in the last 15 yr; in 6 of the 7 cases, MG preceded the SLE; in only 1 reported case and in our case, SLE preceded the MG. The disease that develops later predominates in the prognosis for each patient.