AbstractWe report a familial case of dyschromatosis universalis hereditaria (DUH) which is compatible with an autosomal dominant inheritance. The male proband from Bangladesh presented with randomly distributed hyper‐ and hypo‐pigmented skin lesions of variable shape and size with a mottled appearance. Three additional members of the non‐consangineous family are similarly affected. Light and electron microscopy show normal numbers of active melanocytes, but different amounts of fully melanized melanosomes in hyper‐pigmented and hypo‐pigmented macules. Our findings indicate that DUH is not a disorder of number. It appears to be a disorder of melanosome synthesis rate or in addition melanocyte activity. © 2003 Wiley‐Liss, Inc.