A 43-year-old man with generalized lichen planus demonstrated serum antibodies against autologous lesional skin. Indirect immunofluorescence using serum and papular lesional skin revealed a lichen planus specific antigen found only in the granular layer. The specific tissue antigen was not detected in normal skin from this patient, in normal skin from patients with skin disorders other than lichen planus or in skin from normal control persons. When titers of the serum antibodies against lichen planus antigen were examined before and after a successful therapy a positive correlation of the titer could be found in this patient.