Marihuana and its constitutents delta 9-tetrahydrocannabinol (delta 9-THC) and cannabinol (CBN) were tested for their ability to interact with the androgen receptor in rat prostate cytosol. Smoked marihuana condensate, delta 9-THC, and CBN inhibit specific binding of dihydrotestosterone (DHT) to the androgen receptor with a dissociatin constant of the inhibitors (Li) of 2.1-5.8 X 10(-7)M. in addition, other metabolites of delta 9-THC were also androgen antagonists. This data suggests that the anti-androgenic effects associated with marihuana use results, at least in part, from inhibition of androgen action at the receptor level.