Vitiligo is an acquired depigmentation disorder of great cosmetic importance, affecting 1-4% of the world's population. Vitiligo does not cause physical symptoms but because of its unsightly appearance, particularly on dark or tanned skin it can have considerable impact both psychologically and socially. Many ways of restoring normal colour to the skin have been tried but improvement is usually short-lived. The causes of vitiligo are not yet clearly understood, so many treatments have been developed on the basis of limited scientific evidence. There is no cure, and no way of limiting the spread of the disease has so far been found.