Background: A direct association between human cytomegalovirus (HCMV) infection and the development of restenosis after coronary angioplasty has been suggested. The aim of this prospective study was to evaluate the value of HCMV serology in predicting the clinical outcome after percutaneous transluminal coronary angioplasty (PTCA). Methods and Results: 112 patients undergoing elective PTCA were included in the study. HCMV antibody levels were measured by ELISA. Cardiac events within a follow-up period of 6 months after PTCA were defined as (1) progression or recurrence of anginal complaints and/or a positive exercise test; (2) restenosis that required repeat revascularization. 73% of PTCA patients were seropositive for HCMV. Successful PTCA was achieved in a total of 94 patients, who were followed for 6 months. In 31/94 patients (33%) cardiac events occurred and in 15/94 (16%), this could be related to restenosis. We found no statistically significant difference between seropositive and negative patients with respect to anginal complaints or the need for revascularization. There was no evidence of acute reactivation, since titers of anti-HCMV antibodies did not increase after PTCA. Conclusion: This study shows that the clinical outcome after PTCA is not related to the HCMV serostatus of the patient. Therefore, our data do not support the hypothesis that serological markers of HCMV infection are of clinical importance for the assessment of a patient’s individual risk after PTCA. This does not preclude a role for local reactivation of HCMV at the site of angioplasty.