Vitiligo is a dermatological disorder in man that shows familial aggregation. We performed segregation analysis on data pertaining to vitiligo on members of 147 pedigrees each ascertained through a single proband, and tested various non-genetic, and one-locus and two-locus genetic models. Non-genetic and one-locus genetic models were rejected in favour of a two-locus model postulating epistatic interaction of recessive alleles in the aetiology of vitiligo. The present results show that vitiligo is not a single-locus disorder and substantiate our earlier inference, drawn on the basis of nuclear-family data, of multilocus involvement in the pathogenesis of vitiligo.