OBJECTIVE: To measure the effect of atorvastatin on COX-2 expression in monocytes in patients with acute myocardial infarction (AMI). METHODS: Forty patients with AMI (AMI group) and 18 patients with stable coronary heart disease (control group) were enrolled, and patients with AMI were randomly given routine therapy (n = 20) and routine therapy plus atorvastatin (20 mg/day, n = 20) for a week. Peripheral blood monocytes for each participant including patients with AMI were isolated and cultured for 24 hours. During the culture, monocytes in patients with pretreatment AMI were incubated with celecoxib in different concentration (0, 0.1, 1 and 10 micromol/L). COX-2 mRNA expression in monocytes was measured by reverse transcription polymerase chain reaction (RT-PCR); concentrations of interleukin-6 (IL-6) in supernatant from monocytes and plasma hs-CRP levels were measured by using enzyme-linked immunosorbent assay (ELISA). RESULTS: COX-2 expression in monocytes in patients with AMI (0.92 +/- 0.13) was significantly higher than that in the control subjects (0.19 +/- 0.08), and decreased by 66% after atorvastatin (compared with that on routine therapy, P < 0.05); IL-6 secretions of monocytes in the AMI group (204.8 +/- 45.6 ng/L) increased dramatically compared with those in the control group (40.9 +/- 1.2 ng/L, P < 0.05), and reduced dramatically by 58% when incubated with 10 micromol/L celecoxib (P < 0.05) in a concentration-dependent manner; plasma levels of CRP in the AMI group (43.3 +/- 14.9 mg/L) significantly increased compared with those in the control group (1.7 +/- 0.8 mg/L), and reduced by 62% after atorvastatin (compared with those in the routine therapy group, P < 0.05). COX-2 expression in monocytes in the AMI group was positively correlated with both secretions of IL-6 and plasma level of CRP (r = 0.636 and 0.662, respectively, both P < 0.05). CONCLUSIONS: There is an inflammatory activation in peripheral blood monocytes in patients with early AMI, and the monocytes-derived COX-2 may play an important role in promoting early inflammatory process. Atorvastatin may decrease COX-2 expression in peripheral blood monocytes in patients with AMI and cyclooxygenase-dependent pathway might be correlated with the anti-inflammation mechanism of statin.