The etiology of pemphigus vulgaris is still unknown. Reported familial cases are indicators of a genetic aspect of the disease. We report a brother and sister with simultaneous onset of pemphigus vulgaris. The class II antigens, HLA DRB1*04 and DQB1*03 were detected in both patients. The oral mucosa was affected in one them. Elevation of transaminase levels due to azathioprine therapy was observed in these two cases.