An Nd:YAG laser was used in the treatment of 160 patients with hemangioma from January 1989 to January 1993. Irradiance was between 800 and 1600 W/cm 2 with energy between 400 and 1600 J/cm 2. The best results with almost total restoration were obtained in 21 of the 160 patients (13%). The size of the hemangioma was reduced by more than 50% in 88 cases (55%), by less than 50% in 56 cases (35%), and by a negligible amount in 3 cases (2%). Side effects as found in 160 patients or 10% included slow healing, superficial skin necrosis, and occurrence of scars. Most hemangiomas can shrink by themselves. However, the treatment is needed for cases with risk of various side effects including scar formation, sepsis, bleeding, or abnormal growth of an organ. We concluded that the Nd:YAG laser is a very useful instrument in the treatment of abnormality of blood vessels, such as hemangioma.