Background: We conducted a pilot trial to compare the effectiveness and safety of 2 different treatments in patients with membranous nephropathy and nephrotic syndrome. Methods: To validate the hypothesis that the 2 treatments were equivalent, patients with biopsy-proven membranous nephropathy and nephrotic syndrome were randomly assigned to methylprednisolone alternated with a cytotoxic drug every other month for 6 months (group A) or to intramuscular synthetic adrenocorticotropic hormone administered twice a week for 1 year (group B). Results: The primary outcome measure is cumulative number of remissions as a first event. Fifteen of 16 patients in group A and 14 of 16 patients in group B entered complete or partial remission as a first event. After a median follow-up of 24 months (interquartile range, 15 to 25 months), there were 4 complete remissions and 8 partial remissions in group A versus 8 complete remissions and 6 partial remissions in group B. Median proteinuria decreased from protein of 5.1 g/d (interquartile range, 4.0 to 7.3 g/d) to 2.1 g/d (interquartile range, 0.4 to 3.8 g/d; P = 0.004) in group A and 6.0 g/d (interquartile range, 4.4 to 8.5 g/d) to 0.3 g/d (interquartile range, 0.2 to 1.9 g/d; P = 0.049) in group B. Two patients from each group interrupted treatment because of side effects or inefficacy. Conclusion: Most nephrotic patients with membranous nephropathy responded to either treatment. Proteinuria was significantly decreased with both methylprednisolone and cytotoxic agents or prolonged administration of synthetic adrenocorticotropic hormone, without significant differences between these 2 therapies.