We report a retrospective study of 17 patients with systemic lupus erythematosus who were treated with oral methotrexate given as a mean weekly dose of 8.47 +/- 1.72 mg. Methotrexate treatment resulted in symptomatic improvement in 57% of patients and allowed the reduction of the mean daily dose of prednisone from 16.66 mg initially to 8.99 mg at one year follow-up. Twelve of 17 patients (70.6%) experienced at least one episode of toxicity. Factors which might be associated with toxicity are analyzed. Because of its potential as a corticosteroid-sparing agent, controlled studies of methotrexate for the treatment of systemic lupus erythematosus are indicated.