Sclerotherapy is a microinjection technique for eliminating painful or cosmetically unappealing spider or varicose veins, blood vessel malformations or vascular malformations. Injecting the unwanted veins with a sclerosing solution causes the target vein to immediately shrink, and then dissolve over a period of weeks as the body naturally absorbs the treated vein. Sclerotherapy has been used in the treatment of varicose veins for over 150 years. Modern techniques including ultrasonographic guidance and foam sclerotherapy are the latest variations on this theme. It is a safe, effective treatment with excellent results.