The levels of lipopolysaccharide (LPS)-induced interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) expression in culture of peripheral blood mononuclear cells (PBMC) and the plasma levels of IL-6 and TNF-α in the patients with obstructive sleep apnea syndrome (OSAS) were measured and the relationship between OSAS and IL-6 or TNF-α expression studied. Both IL-6 and TNF-α were detected by using ELISA in 22 patients with OSAS and 16 normal controls. The levels of LPS-induced IL-6 (787.82±151.97 pg/ml) and TNF-α (4165.45±1501.43 pg/ml) expression in the supernatant of the culture of PBMC and plasma level of IL-6 (50.67±4.70 pg/ml) and TNF-α (299.09±43.57 pg/ml) in the patients with OSAS were significantly higher than those in the normal controls (in the supernatant of the culture of PBMC: 562.69±197.54 pg/ml and 1596.25±403.08 pg/ml respectively; in the plasma: 12.69±2.75 pg/ml and 101.88±21.27 pg/ml respectively). There were significantly positive correlation between the levels of IL-6 and TNF-α and the percentage of time of apnea and hyponea, as well as the percentage of time spending at SaO2 below 90 % in the total sleep time. It was concluded that LPS-induced IL-6 and TNF-α levels as well as plasma IL-6 and TNF-α levels in the patients with OSAS were up-regulated, which may be associated with the pathogenesis of OSAS.