Fifteen years ago we began a prospective study using alternate case treatment with prednisone in patients with pulmonary function abnormalities due to sarcoidosis. Twenty-five patients were divided into treatment and control groups that were similar in sex, age, race, degree of pulmonary dysfunction, and duration of disease. Evaluation included complete spirometric studies, single-breath carbon monoxide diffusion capacity, and arterial blood gases. Follow-up studies at six months, one to two years, and ten to 15 years show no difference between the treated and untreated groups. Improvement or deterioration in pulmonary function of individual patients in the treated group was reflected in the control group, even in those patients with a diffusing capacity and forced vital capacity less than 65 percent of predicted. Data from this long-term study fail to show any benefit of short-term use of steroids in therapy for pulmonary sarcoidosis.