Objective To identify the relationship between the concentration of endothelin and the progression of primary biliary cirrhosis (PBC) by measuring the endothelins (ET) level of PBC patients as well as the PBC patients who were treated withUDCA. In addition, the role of ET on regulating TNF-α and IL-6 secretion of PBMC is explored. Methods The ET level in serum of 24 PBC patients was measured by ELISA. Then PBMCs were stimulated by ET and the concentration of TNF-α, IL-6 levels were measured by ELISA. cDNAs from all RNA extracted from the PBMCs were synthesized, and the expression level of TNF-α was detected by semi-quantitative RT-PCR. Results ET concentration in PBC patietns was significantly higher than healthy controls [(6.0±2.8) vs(2.3±3.4) pg/ml, P<0.05]. The level of ET was not related to other serum biochemical markers.. After UDCA treatment, the level of ET in PBC patients had decreased [(7.5±1.6) vs (6.2±2.7) pg/ml, P=0.084]. After ET-1 stimulation, the secretion of TNF-α by PBMCs in PBC patients increased significantly, and the secretion of 1L-6 decreased, but without statistically significant difference. RT-PCR showed that the expression level of TNF-α mRNA increased significantly after ET-1 stimulation. Conclusion The level of ET in PBC serum is much higher than that of the healthy controls. UDCA treatment can decrease the level of ET in PBC patients. ET can increase the expression of TNF-α mRNA. The increased secretion of TNF-α further activates inflammatory cytokine cascade that plays an important role in the development of PBC.