In order to evaluate the efficacy of topical khellin the vitiligo macules of one side only were painted in 41 patients with a 2% solution of khellin in acetone and propylene glycol (90 and 10% respectively) and exposed to sunlight for a period of 4 months with 3 weekly applications and with exposure times up to 90 min. The macules of the other side were treated in 36 of the 41 patients with acetone and propylene glycol only and sun-exposed with the same schedule, while in the remaining 5 patients they were neither treated with khellin or placebo nor sun-exposed. No significant difference was evidenced between the khellin and placebo-treated sides: no excellent result (repigmentation more than 75% of the affected area) was found, and good results (repigmentation more than 50%) were found in 24.9% of khellin- plus sunlight-treated macules and in 22.3% of placebo- plus sunlight-treated macules.