Anandron administration (300 mg/daily) to 16 human normal genetic male volunteers (who opted for male to female gender transformation) induced clinical signs of feminisation during 8 weeks of treatment. More than 2-fold increase in blood luteinising hormone and testosterone was measured while follicle stimulating hormone remained without any change in the levels. Prolactin showed a slight but significant increase at 8 weeks of treatment. The prostate size measured in 6 subjects using transrectal ultrasonography before and at 8 weeks of anandron treatment showed no change. The prostate size measured in 6 subjects who received androcur (100 mg/daily) in combination with ethinyl estradiol (100 μg/daily) for longer than 18 months did not differ compared to pre-treatment size. However, the prostate histology showed a clear predominance of stromal components with a significant reduction in the number of acini. The epithelial cells appeared atrophic. Histology of the testes showed a readily observable reduction in tubular and interstitial cells. The monodispersed cells prepared from the testes consisted of Leydig and non-Leydig cells. These cells responded to stimuli (hCG and Pregnenolone) in terms of an increase in testosterone synthesis in vitro. Anandron treatment of intact mature male rats increased the blood testosterone level. Estrogen administration dramatically reduced the anandron induced increase in testosterone to castration level. The benefits of a combination of low doses of anandron and estrogen for achieving an effective anti-androgenic action are presented.