Studies suggested that the activation of the coagulation system and inflammation mutually may reinforce each other in some cases. In this study, we test the plasma tissue factor (TF) and interleukin 18 in patients with coronary heart disease (CHD) before and after treatment and aim to determine whether this relationship exists in patients with CHD. The levels of plasma TF and IL-18 from 118 patients with CHD were determined by enzyme-linked immunosorbent assay. One hundred and eighteen patients were divided into acute coronary syndrome (ACS) group (61 cases) and stable angina pectoris group (51 cases). Upon admission, patients with ACS showed significantly higher levels of plasma TF and interleukin 18 compared with those having stable angina (P < 0.01), and the levels decreased after treatment; levels of plasma TF and interleukin 18 of patients with ACS were closely and positively correlated (r = 0.74, P < 0.01); after 7 days of treatment, the correlation decreased (r = 0.53, P > 0.05); and after 1 month of treatment, no significant correlation can be detected between the two (r = 0.18, P > 0.05). The results suggest that levels of plasma TF and interleukin 18 are significantly increased in patients with ACS, and there is significant correlation between the two, indicating an interaction between inflammation and coagulation in patients with ACS and an important role of these two in the occurrence and development of such disease.