Abstract: [Abstract] Objective To explore the mechanism of apoptosis in the labial glands of patients with primary Sjogren’s syndrome(pSS). Methods Samples from 70 clinically suspected primary Sjogren’s syndrome (pSS) patients were collected. Based on the results of labial gland biopsy, 40 cases of positive pathological grade served as experimental group, and the rest 30 were classified as control group. Immunohistochemistry was used to examine Bax protein in labial glands of two groups. The homogenate of labial glands was prepared; the mitochondria were extracted; the CytC content was detected. SPSS14.0 software package was used for statistical analysis. Results In experimental group, the expression of Bax protein mainly existed in epithelium and ductal epithelial cells (with IOD being 51.20±0.57) while in the control group, positive staining was mainly found in stromal cells(with IOD being 22.03±0.25), and there was a significant difference between two groups. In experimental group, the content of CytC in cytoplasm was 5.98±0.24, and the content of mitochondrial CytC was 0.44±0.14, while those of the control group were respectively 2.19±0.29 and 0.87±0.09. There were significant differences between them. Conclusions The pathogenesis of pSS is related to the apoptosis that is induced by Bax protein and CytC.