The plasma levels of inflammatory cytokine interleukin-6 (IL-6) and anti-inflammatory cytokine interleukin-10 (IL-10) in the patients with unstable angina or stable angina were determined and compared. In 30 patients with unstable angina and 22 patients with stable angina, plasma levels of IL-10 and IL-6 were detected by ELISA and plasma lipid parameters by lipid research clinical methods respectively. The results showed plasma levels of IL-10 were significantly lower in unstable angina group than in stable angina group (P=0.005), while those of IL-6 were significantly increased in unstable angina group as compared with those in stable angina group (P=0.039). There was a significantly negative correlation between IL-10 and IL-6 in patients with unstable angina (r=−0.41,P=0.003). In the unstable angina group, IL-6 levels were obviously positively correlated with TC (r=0.314,P=0.023), but not with TG and HDL. There were no significant correlations between IL-10 and plasma lipid parameters. It was suggested that the decreased IL-10 and increased IL-6 might be associated with the atheromatous plaque stability and progression of coronary heart diseases. IL-10 may play an important role in preventing coronary vascular lesions.