Statin therapy reduces clinical events in patients with stable coronary artery disease. Recent data indicate that the beneficial effects of statin therapy may also extend to patients experiencing an acute ischemic coronary event. However, the potential role of statins to further modify clinical outcome in patients undergoing coronary stent implantation has not been addressed. Therefore, we investigated whether the initiation of statin therapy immediately after successful coronary stent implantation improves short-term clinical outcome in 704 patients (335 patients with stable angina pectoris [AP], 224 patients with unstable AP, and 145 patients with Q-wave acute myocardial infarction [AMI]). Compared with the lowest risk group (patients with stable AP receiving statin therapy), patients with unstable AP (RR 6.9, 95% confidence interval [CI] 1.5 to 31, p = 0.004) and patients with Q-wave AMI (RR 7.6, 95% CI 1.5 to 37, p = 0.004) experienced an increased risk for the occurrence of the primary combined end point of cardiac death and AMI. Importantly, initiation of statin therapy abrogated the increased risk in patients with unstable AP to the level of patients with stable AP receiving statin therapy (RR 1.5, 95% CI 0.2 to 11, p = 0.7). In contrast, statin therapy did not affect the RR in patients with Q-wave AMI during 6-month follow-up (RR 7.9, 95% CI 1.6 to 39 vs RR 7.6, 95% CI 1.5 to 37, p = NS). The beneficial effects of statin therapy after successful coronary stent implantation in unstable AP were most prominent during the first 4 weeks after the ischemic episode. Statins appear to contribute to the rapid transformation of unstable coronary artery disease into a stable condition with a very low event rate over the forthcoming 6 months in patients with unstable AP undergoing successful coronary stent implantation.