Tongkat ali (Eurycoma longifolia), also known as longjack or Malaysian ginseng, is an herb from Southeast Asia. The main bioactive components in tongkat ali are the quassinoid compounds (eurycomanone and eurycomanol), eurycolactones, canthin-6-one metabolites, eurylene and teurilene (derivatives of squalene) and eurypeptides. Supplementation may increase total testosterone in healthy and hypogonadal men, improve erectile function and alleviate symptoms of erectile dysfunction, increase fertility, and enhance sexual function and well-being.