Rate constants for methanolysis of a group of C14 labelled methyl esters of steroidal carboxylic acids were determined by a radiochemical procedure in order to examine the effect of interposition of a methylene group between the steroidal ring system and the carbomethoxy group on the differential reactivity of epimeric esters. The results are of interest regarding the i'lictors controlling the differential rate of alkaline hydrolysis of acyl derivatives of epimeric axial and equatorial alicyclic alcohols.For specific comparison with the methyl easter rate constants, those for the hydrolysis of the epimeric 5-acetoxy-5-a-cholestanewere also measured, again by a radiochemical procedure.