Sarms are Selective Androgen Receptor Molecules, they are synthetic ligands that bind to androgen receptors. Selective Androgen Receptor Modulators (SARMs) are a class of therapeutic compounds that have similar anabolic properties to anabolic steroids, but with reduced androgenic (producing male characteristics) properties. As an example, the androgen receptor is activated by binding androgens, such as testosterone. Unlike anabolic steroids, which bind to androgen receptors in many tissues all over the body, individual SARMs selectively bind androgen receptors in certain tissues, but not in others.

In medical settings, this could be very useful for stimulating specific tissue growth like muscle and bone, while avoiding unwanted side effects in other tissues like the liver or skin. Sarm is being evaluated as a clinical treatment for muscle wasting caused by several diseases, such as osteoporosis, cancer, heart failure, chronic obstructive pulmonary disease, end-stage liver disease, end-stage renal disease, and HIV.