BACKGROUND AND HYPOTHESIS: Lipoprotein(a) [Lp(a)] and renal dysfunction are both independent risk factors for cardiovascular disease. However, it remains unclear whether renal function mediates the association between Lp(a) and cardiovascular outcomes in patients undergoing percutaneous coronary intervention (PCI). METHODS: From a large prospective cohort study, 10 435 eligible patients undergoing PCI from January 2013 to December 2013 were included in our analysis. Patients were stratified into three renal function groups according to their baseline estimated glomerular filtration rate (eGFR) (<60; 60-90; ≥90 ml/min/1.73 m). The primary endpoint was a composite of all-cause death, nonfatal MI, ischemic stroke, and unplanned revascularization [major adverse cardiac and cerebrovascular events (MACCE)]. RESULTS: Over a median follow-up of 5.1 years, a total of 2144 MACCE events occurred. After multivariable adjustment, either eGFR <60 ml/min/1.73 m or elevated Lp(a) conferred a significantly higher MACCE risk. Higher Lp(a) was significantly associated with an increased risk of MACCE in patients with eGFR <60 ml/min/1.73 m. However, this association was weakened in subjects with only mild renal impairment and diminished in those with normal renal function. A significant interaction for MACCE between renal categories and Lp(a) was observed (= 0.026). Patients with concomitant Lp(a) ≥30 mg/dl and eGFR <60 ml/min/1.73 m experienced worse cardiovascular outcomes compared with those without. CONCLUSION: The significant association between Lp(a) and cardiovascular outcomes was mediated by renal function in patients undergoing PCI. Lp(a)-associated risk was more pronounced in patients with worse renal function, suggesting close monitoring and aggressive management are needed in this population.