AbstractCatalytic reduction of 3β‐hydroxyandrost‐4‐ene‐17‐one (I) with tritium gas gave a mixture of 3β‐hydroxy‐5α‐androstane‐17‐one (II) and 3β‐hydroxy‐5α‐androstane‐17‐one (III). Oxidation of compound II followed by alkaline equilibration resulted in 37% loss of label from position 4. 5α‐Androstane‐3,7‐dione (IVa) was converted via the 2,4‐dibromide to androst‐4‐ene‐3,7‐dione (VIIIa) with 43% loss of radioactivity from position 5. Chloranil dehydrogenation and alkaline equilibration experiments have shown that the additional label was at C‐6α. The distribution and configuration of label in