Pemphigus vulgaris (PV), a rare autoimmune mucocutaneous blistering disorder, has been reported with incidence of 0.1-0.5 cases per 100,000 individuals worldwide per year. It is slightly more common in women and occurs primarily in adults during the 5 th or 6 th decade of life. The etiology of PV is uncertain but is supposed to be mediated by circulating immunoglobulin G (IgG) autoantibodies against the desmosomal cadherins, desmoglein 1 and 3. Biopsy, light microscopic examination, and additional adjuvant tests, such as immunofl uorescence studies can be used to establish the diagnosis. In most cases (70-90%), the fi rst signs of disease appear on the oral mucosa but most patients with oral lesions are initially misdiagnosed and treated improperly for months or years. If these patients are misdiagnosed or left untreated, PV may be fatal with a mortality rate ranging from 60% to 90%. Therefore, here we are trying to discuss basics of diagnosing and treating PV with oral lesions with the help of a case report.