Evaluation of treatment of rheumatoid arthritis with prednisone for more than a year leaves little doubt that prednisone and the related steroid, prednisolone, are steroids superior to cortisone, hydrocortisone, and corticotropin. Three important advantages of prednisone have become established, namely, a lack of sodium retention, the absence of increased potassium excretion, and the unlikelihood of the production of hypertension during its use. The incidence of duodenal ulcer was found to be no greater than that encountered in the normal population. Thorn tests were done in a large group to determine possible depression of the adrenal gland. Remission or improvement can sometimes be obtained with prednisone in patients whose treatment with cortisone or hydrocortisone has been unsatisfactory because of undesirable effects or diminution in effect.