Blisters following minor trauma characterize epidermolysis bullosa, a group of hereditary diseases of the skin. In the simplex type, epidermal basal cells are fragile, and mutations of genes encoding keratin intermediate filament proteins underlie that fragility. In the dystrophic types, the causative mutation appears to be in the gene encoding type VII collagen, which is the major component of anchoring fibrils. These recent findings afford solid evidence that at least one function of the cytoskeletal intermediate filament network is the provision of mechanical stability and that anchoring fibrils indeed do anchor the epidermis to the underlying dermis.