Aim: The aim of this study was to analyse the nephrological morbidity after myocardial revascularization. Methods and results: We analysed the pre- per and postoperative data of 3815 patients who underwent a primary isolated coronary bypass grafting between January 1987 and December 1995. Nephrological complications were divided into renal dysfunction and requiring dialysis. The increase in nephrological complications (1.2–4%) is the result of an increase of patients with renal dysfunction. Unifactorial risk analysis identified age, diabetes, hypertension, nephrological pathology, perfusion time, aortic cross-clamp time, emergency operation and perioperative myocardial infarction as risk factors. Multifactorial risk analysis identified age, diabetes, hypertension, nephrological pathology, perfusion time, perioperative myocardial infarction and the cohorts operated upon in 1990–92, 1993–95 as independent risk factors for renal dysfunction, and age, nephrological pathology and perioperative myocardial infarction for those needing dialysis. Conclusion: Several variables have been identified as risk factors for nephrological complications; especially important are pre-existing nephrological pathology and perioperative myocardial infarction.