A 46-year-old woman presented with a two year history of pruritic erythematous plaques with blisters, as well as oral erosions. Even though the cutaneous lesions fit best with dermatitis herpetiformis, bullous pemphigoid or pemphigoid gestationis, the histologic examination revealed eosinophilic spongiosis, most compatible with some form of pemphigus. The identification of intercellular IgG deposition on direct immunofluorescence and circulating IgG pemphigus antibodies on indirect immunofluorescence microscopy led to diagnosis of pemphigus herpetiformis. This rare form of pemphigus does not often involve the oral mucosa. In our patient, the explanation is that she had antibodies against desmoglein 3 but not desmoglein 1. Treatment with prednisolone and azathioprine caused rapid and complete healing.