A 56 yr old woman developed a vesicular and bullous eruption followed by an efflorescence of lichenoid papules. The clinical and histologic features of this case were consistent with a diagnosis of lichen planus pemphigoides. Direct and indirect immunofluorescence studies demonstrated in vivo-bound and circulating IgG [immunoglobulin G] with specificity for the epidermal basement membrane zone. A common pathogenic immunologic mechanism may exist for lichen planus and lichen planus pemphigoides, which are probably clinical variants of a similar disease process.