The myotrophic and nitrogen retaining effects of five steroids (methyltestosterone; methylandrostenediol; 17[alpha]-methylandrosta-4,6-diene-17[beta]-ol-3-one; 19-nor-17[alpha]-methylandrost-5 (10) eno-17[beta]-ol-3-one and 17[beta]-hydroxy-17[alpha]-methylandrost-4-eno[3,2-c]pyrazole were compared with those of testosterone propionate. The myotrophic potencies and 95% confidence limits of the five compounds relative to testosterone propionate at 100 were: methyltestosterone, 63 (46-90); methylandrostenediol, 6.7 (4.4-9.8); methylandrostadienolone, 4.6 (3.7-6.5); methylnorandrosten-olone, 30 (21-44) and hydroxystenazole, 8.0 (5.1-11.4), whereas the nitrogen retaining potencies were: methyltestosterone, 17 (4-69); methylandrostenediol, 2.5 (estimated); methylandrostadienolone, 12 (4.8-29); methylnorandrostenolone and hydroxystenazole inactive. Agreement existed between the myotrophic and nitrogen retaining potencies of methyltestosterone, methylandrostenediol and methylandrostadienolone. A disparity between the myotrophic and nitrogen retaining activities of methylnorandrostenolone and hydroxystenazole was noted in that each was myotrophic but neither supported nitrogen retention. The latter two compounds were observed to be estrogenic. These data indicate that inherent estrogenic properties or estrogenic contamination of a compound may interfere more with the demonstration of nitrogen retaining effects than with myotrophic effects.