Objective We aimed to investigate the effect of statin therapy in cardiovascular outcome in patients with mild to moderate coronary artery stenosis detected by coronary artery computed tomography (CT). Methods and Result A total 13,512 patients who are asymptomatic or have atypical chest pain who underwent CT were evaluated. Of these, we included patients with mild to moderate coronary artery stenosis (1-69%) on CT. Those with previous history of revascularization or prior use of statin therapy were excluded. Propensity score matching was performed to adjust baseline characteristics including age, presence of hypertension or diabetes mellitus, coronary artery calcium score, blood pressure, lipid profiles, fasting blood sugar and degree of stenosis. After propensity score matching, 643 statin users and 643 statin non-users were compared. In both statin users and non-users, total cholesterol and LDL-cholesterol levels were significantly reduced at follow up, compared to the baseline values (218짹41 to 171짹36 in statin users and 213짹37 to 191짹39 in statin non-users for total cholesterol, 118짹30 to 86짹28 in statin users and 116짹28 to 105짹29 in non-users for LDL-cholesterol, all p<0.001). During median follow up of 26 months, 16 (1.3%) patients had cardiovascular event defined as cardiovascular death or acute coronary syndrome. The statin users and non-users did not show significant difference in cardiovascular outcome, defined as 1) cardiovascular death or acute coronary syndrome (p=0.378), and 2) stroke in addition to 1) (p=0.196). Conclusion Statin therapy in patients with mild to moderate coronary artery stenosis on 64-slice multidetector CT has no beneficial effects in reducing adverse cardiovascular events. Use of statin in patients with mild to moderate stenosis should be based on individual risk, rather than degree of stenosis detected by CT.