Hydroxyflutamide (developmental code SCH-16423; also known as 2-hydroxyflutamide, HF, and OHF) is a nonsteroidal antiandrogen (NSAA) and the major active metabolite of flutamide, which is considered to be a prodrug of hydroxyflutamide as the active form. It has been reported to possess an IC<sub>50</sub> of 700 nM for the androgen receptor (AR), which is about 4-fold less than that of bicalutamide.