This herb is still little known in the west for its medicinal properties but is widley used in Indian ayurvedic medicine where it is known as "gokshura". In ayurveda it is considered a tonic and its effects are sometimes compared to those of ginseng, although the two herbs work through entirely different mechanisms. Tribilus terrestris supplements are mainly promoted for the enhancement of sexual health through their ability to raise hormone levels. Independant studies have verified that the herb does indeed raise hormone levels but only modestly, leaving them within the normal range. A number of sources state that Tribulus terrestris elevates testosterone in particular by stimulating production of gonadotropin-releasing hormone (GnRH). As such it has become popular with weight-lifters despite research indicating that the herb only raises testosterone considerably when there is a deficiency to start with. Tribulus terrestris also has powerful effects on the liver stimulating bile flow and increasing levels of glutathione. Other benefits reported include immune stimulation, anti-fungal properties and heart protective effects.

(from iHerb.com)