Drug-induced lesions of oral mucosa are well-established side effect of different commonly used drugs. A female patient under treatment for hypertension with an angiotensin-converting enzyme inhibitor (ACE inhibitor), lisinopril, developed blisters and ulcerations on oral mucosa 3 weeks after lisinopril intake. Due to clinical finding drug-induced pemphigus was considered. However, direct and indirect immunofluorescence analysis revealed no autoantibodies that are commonly present in pemphigus while histological study suggested allergic reaction. Lisinopril was discontinued from further therapy and after a month after her first arrival patient has experienced complete remission of the disease. This case raises the question, whether the term pemphigus in drug-induced reactions could be used when immunopathological criteria for pemphigus are not fulfilled.