The adverse effects of corticosteroid therapy while treating 830 patients suffering from leprosy reaction (type 1 = 581; type 2 = 249) are presented. Some of the adverse effects were cosmetically distressing, while others were disabling. Patients suffering from type 2 reaction--because of the tendency of the reaction to recur over a long time--needed steroids for a longer duration; hence, adverse effects were more frequent. Measures to counter some of the adverse effects are suggested and the need to identify drugs with potentially less adverse effects is emphasized.