Th17 cells, which mainly produce interleukin (IL)-17, have been suggested to play a critical role in the pathogenesis of autoimmune diseases. The plasticity of Th17 cells, in which these cells shift to a Th1 phenotype in the presence of IL-12, has recently been reported. However, the role of IL-17 in Sjögren's syndrome (SS) and Mikulicz's disease (MD) currently remains unknown. The submandibular salivary gland and lymph node of a MD patient and the salivary glands of 15 SS patients were collected. IFN-γ+ cells, IL-17+ cells, and IFN-γ+ IL-17+ cells were detected by immunohistochemical staining. IFN-γ+ cells, IL-17+ cells, and IFN-γ+ IL-17+ cells were detected in the submandibular salivary gland and lymph node of the MD patient and salivary glands of the 15 SS patients. IFN-γ+ IL-17+ cells in the salivary glands of patients were speculated to be Th1/Th17 cells in the present study. Th1/Th17 cells are known to be derived from Th17 cells and differentiate into Th1 cells, and IL-17-derived Th1 cells have been suggested to induce the deterioration of juvenile idiopathic arthritis (JIA). Thus, Th1/Th17 cells may play an important role in the pathogenesis of SS and MD. IFN-γ+, IFN-γ+ IL-17+, and IL-17+ cells were detected in the submandibular salivary gland and lymph node of a MD patient and the salivary glands of 15 SS patients.