The aim of this 2-year study was to test the hypothesis that folic acid, vitamin B12 and sun exposure could be helpful in treating vitiligo. One hundred patients with vitiligo were treated with oral folic acid and vitamin B12 after being informed that sun exposure might enhance repigmentation. They were requested to keep a record of sun exposure in summer and UVB irradiation in winter. The minimal treatment time suggested was 3-6 months but should be longer if improvement was achieved. Clear repigmentation occurred in 52 patients, including 37 who exposed their skin to summer sun and 6 who used UVB lamps in winter. Repigmentation was most evident on sun-exposed areas, where 38% of the patients had previously noted repigmentation during summer months. Total repigmentation was seen in 6 patients. The spread of vitiligo stopped in 64% of the patients after treatment. Folic acid and vitamin B12 supplementation combined with sun exposure can induce repigmentation better than either the vitamins or sun exposure alone. Treatment should continue as long as the white areas continue to repigment. Further studies are needed to determine ideal minimal dosages of vitamins and UV exposure, as well as treatment time.