beta-methyl-17-keto steroids 18a and 19a (Ki = 3.1 and 5.3 nM, respectively) as well as the 6 beta- alcohol 5a (Ki = 6.0 nM) were high, and their apparent Ki values were lower than that of the parent 6-unsubstituted 3-deoxy steroid 1 (Ki = 6.8 nM). Elongation of the methyl group decreased affinity for aromatase in relation to carbon number of the alkyl chain in each series, in which the 6 alpha- alkyl steroids 18 essentially