Apart from nonspecifically altered laboratory data, enhanced chemotaxis of polymorphonuclear leukocytes to chemotactic stimuli, HLA-B5 and circulating cytotoxic lymphocytes for oral epithelial cells were demonstrated in a 21-year-old patient suffering from Behçet’s disease (BD). Pathological liver function became indicative of concomitant hepatic involvement. The pathogenetic role cytotoxic lymphocytes have on the oral mucosa in BD is discussed.