Recessive dystrophic epidermolysis bullosa is a severe mutilating genodermatosis. Previous ultrastructural demonstrations of altered anchoring fibrils, and recent genetic linkage analyses have suggested that type VII collagen, the major component of anchoring fibrils, is a candidate gene. We have identified a homozygous methionine–to–lysine mutation in two affected siblings, while their unaffected mother and half–brother are heterozygous carriers. The mutation resides in a highly conserved region of the C–terminus of type VII collagen, strongly suggesting that it is the cause of the disease in this family.