Three cases of persistent erythema multiforme, two of unknown aetiology and one precipitated by influenza are reported. Lesions were widespread, mostly atypical in appearance and regressed in response to immunosuppressants (systemic steroids and/or azathioprine) or, in one case, to dapsone. One patient developed erythroderma responding eventually to etretinate. Histology in all patients was consistent with the mixed, epidermodermal pattern of erythema multiforme. There were no significant laboratory abnormalities nor marked symptomatology apart from itching. The persistent form appears to belong to the spectrum of erythema multiforme being heterogeneous with respect to inducing stimuli, including viral antigens, neoplastic or inflammatory disease or unknown causes. Whenever it is possible, treatment should be adjusted depending on the causative agent.