YK-11 is a synthetic steroidal selective androgen receptor modulator (SARM). It is a gene-selective partial agonist of the androgen receptor (AR) and does not induce the physical interaction between the NTD/AF1 and LBD/AF2 (known as the N/C interaction), which is required for full transactivation of the AR. The drug has anabolic activity in vitro in C2C12 myoblasts and shows greater potency than dihydrotestosterone (DHT) in this regard. It has been investigated as a potential treatment for sepsis-induced muscle wasting in animal studies. 

This Sarm can significantly increase lean muscle mass and strength beyond training and nutrition alone. It stimulates follistatin production, a potent myostatin inhibitor. 

Those who use SARMs and SARM-like compounds commonly follow 8 week cycles for lean muscle gain and strength enhancement then take the following 8 weeks off. Recommended daily dose for YK-11 is anywhere from 10-15mg for optimal results.