The oral activity of 34 steroids administered by stomach catheter was evaluated in castrated rats using the weights of the seminal vesicle glands and ventral lobe of the prostate glands as independent parameters of androgenicity and the weight of the levator ani muscle was used as an index of anabolic activity. 17α-Methyltestosterone was used as the reference standard. A study of various modifications of the A-ring revealed that biological activity was consistent with any one of several distinct changes and did not appear to be related to the electron density in any specific position in the A-ring. Nineteen of the steroids were more potent anabolically than the standard and the eight most active analogues had relative myotrophic potencies ranging from 420–1200% and myotrophic to androgenic ratios ranging from 4.1 to 9.3, respectively. Both saturated and unsaturated 17α-methyl derivatives were represented in this latter group. In general, the most potent compounds anabolically were also among the most active androgenically. Estimates of androgenic potency obtained from the seminal vesicle response were similar to those obtained from the ventral prostate response. The most active anabolic compound (1200%) was the 2-dehydro derivative of 17α-methyl-5α-androstan-17β-ol. The widest separation between anabolic and androgenic activities, myotrophic to androgenic ratio of 9.3, was produced with the 2-dehydro-1α-methyl derivative.