A Th1/Th2 cytokine imbalance with a predominance of Th1 cytokines has been suggested to be of pathogenic importance in Wegener's granulomatosis. To evaluate the role of Th1/Th2 cytokines in Wegener's granulomatosis, the subsets of Th1, Th2, Tc1 and Tc2 cells from patients with active Wegener's granulomatosis were examined by intracellular cytokine flow cytometry. The population of Tc1 cells (72.0 +/- 14.4 per cent) in Wegener's granulomatosis was significantly increased compared with Tc1 cells (37.3 +/- 14.6 per cent) in control (p<0.05). Th1, Th2 and Tc2 cells in Wegener's granulomatosis were not significantly increased compared with the control cells. These results indicate that the predominance of Tc1 cells might contribute to the mechanism of the pathogenesis of Wegener's granulomatosis.