The genus Taraxacum is a member of the family Asteraceae, subfamily Cichorioideae, tribe Lactuceae and widely distributed in the warmer temperate zones of the Northern Hemisphere. The perennial weed has been known since ancient times for its curative properties and has been utilized for the treatment of various ailments such as dyspepsia, heartburn, spleen and liver complaints, hepatitis and anorexia. However, its use has mainly been based on empirical findings. This contribution provides a comprehensive review of the pharmacologically relevant compounds of Taraxacum characterized so far and of the studies supporting its use as a medicinal plant. Particular attention has been given to diuretic, choleretic, anti-inflammatory, anti-oxidative, anti-carcinogenic, analgesic, anti-hyperglycemic, anti-coagulatory and prebiotic effects. Finally, research needs such as quantification of individual Taraxacum constituents and assessment of their pharmacological activities in humans have briefly been outlined.