The administration of phenylalanine (Phe) combined with UVA exposure was found to be effective in treating vitiligo. Twenty-one patients with vitiligo were divided in two groups: eleven patients were treated with oral L-Phe in a dose of 100 mg/kg body weight and with UVA exposure and ten patients were treated with oral L-Phe in a dose of 100 mg/kg body weight and with UVA exposure. In addition, in the second group, a cream containing 10% L-Phe was applied to the vitiliginous areas. The best results occurred in the second group. No side effects were found in either group.