By means of renal biopsy and light, immunofluorescence, and electron microscopy, a diagnosis of membranous nephropathy (MN) was made in 100 patients. The nephrotic syndrome was present in 83 of these patients. 65 of the patients were men and 35 were women. The average period of follow-up was 99.8 months. As judged by the incidence of death and of improvement or complete healing, the women fared better than the men, whether given high-dose alternate-day prednisone therapy or not. The incidence of improvement or complete healing in the patients given prednisone was higher than the reported for patients who were not given corticosteroids. We have shown that occurrence of MN is more frequent in women than men and the course of MN is more benign in women than in men; alternate-day prednisone therapy appears to be beneficial in patients with MN.