Diversification of the androgen response in rat prostate, rat uterus and mouse kidney cannot be explained by differences in the cytosolic androgen receptor proteins extracted from these organs. On the other hand, metabolism of the steroid hormone in the target cell and interaction in the target cell with non specific binding proteins could intervene in the diversification of the androgen response. As far as the steroid 5α-reductase is concerned, the absence in a given target cell of enzymes which compete for its substrate (testosterone) or which inactivate its reaction product (dihydrotestosterone) are probably of more importance than the apparent “nuclear” localisation of the enzyme. In particular, steroid 5α-reductase may play a rate limiting role in the production of dihydrotestosterone-receptor complex in the prostate. Transformation of 3α-androstanediol into dihydrotestosterone at the target organ level is catalyzed predominantly by the NAD(H)-dependent microsomal 3α-HSD. The high activity of this enzyme in several tissues such as the rat prostate, the rat kidney and the rat exorbital lacrimal gland may explain the particular responsiveness of these organs to exogenously administered 3α-androstanediol. The question of whether testosterone-receptor complexes and dihydrotestosterone-receptor complexes have different physiological activity remains to be investigated. Preliminary experiments indicate that both receptor complexes can associate with nuclear chromatin in vitro.