RU58841 (also known as RU-58841, PSK-3841 or HMR-3841) is a compound that has been garnering attention for RU58841 phenomenal response to hair growth. Anti-androgens have potential to be used to treat some 'male' cancers such as prostate cancer, as well as possibly targeting skin conditions including acne and male-pattern baldness. RU58841 differs from other anti-androgens in that rather than trying to reduce or block the production of testosterone or DHT, it focuses on the testosterone receptor.

RU58841 is a specific androgen receptor antagonist or a so called anti-androgen. This non steroidal topical androgen antagonist was investigated for therapeutic value in androgenetic alopecia and acne.