Eighty-five corticosteroid dependent patients with respiratory diseases requiring alternate day prednisone were studied for certain adverse effects that have been reported to be associated with corticosteroid therapy. The mean age of the patients was 52 years, the average years of prednisone therapy was 5.3, and the mean dose of alternate day prednisone was 26.2 mg. In this group of 85 patients the prevalence of hypertension, peptic ulcer disease, pathologic fractures and psychosis was not statistically increased over that of the general population. None of the patients was diagnosed as having steroid-induced psychosis, pancreatitis or tuberculosis. One patient developed aseptic necrosis of the hip; however, she received daily prednisone for approximately 3.2 years before being converted to an alternate day schedule. Our results demonstrate that alternate day corticosteroid therapy can be used without significant risk of adverse effects in patients in whom it is essential for control of respiratory disease.