AC-262536 is a selective androgen receptor modulator (SARM; Ki = 5.01 nM).1 It is also a partial agonist of the androgen receptor (EC50 = 1.58 nM in a luciferase assay). AC-262536 is selective for the androgen receptor over a panel of 47 additional human nuclear receptors at 10 µM. It inhibits dihydroxytestosterone-induced proliferation of LNCaP prostate cancer cells when used at concentrations of 0.1 and 1 µM. AC-262536 (3, 10, and 30 mg/kg) reduces plasma luteinizing hormone levels and increases levator ani muscle weight, a marker of anabolic activity, in castrated rats. It exhibits smaller increases in prostate gland and seminal vesicle weight, markers of androgenic activity, compared with testosterone in the same model.