Variegate porphyria (VP) is an autosomal dominant disease characterized in adults by mechanical fragility and blistering of sun-exposed skin or acute visceral and neurological manifestations. The laboratory diagnosis of VP depends on a search for high levels of coproporphyrin and protoporphyrin in the feces. Variegate porphyria has been infrequently diagnosed in the United States. In this study of five New England families with VP, there were nine manifest, six latent, and six questionable cases among 40 individuals studied. This report reviews the diagnostic approach to and treatment of affected individuals and their families.