AIMS: The purpose of this study was to assess renal dysfunction as an independent predictor of mortality after acute myocardial infarction. METHODS: The study population was 6252 patients with a myocardial infarction admitted alive from 1990 to 1992. The mortality status was obtained after at least 6 years. RESULTS: Cox proportional-hazards model demonstrated that the unadjusted risk ratio associated with a calculated creatinine clearance < or =40 ml x min(-1) compared to a clearance above 85 ml x min(-1) was 7.1 (95% confidence interval 6.2-8.0). Adjustment for multiple available covariates reduced this risk to 2.0 (1.6-2.4). The unadjusted risk ratio associated with clearance from 41 to 55 ml x min(-1) and from 71 to 85 ml x min(-1) was 3.7 (3.3-4.2) and 1.5 (1.3-1.7) respectively, but after adjustment for all available variables these risks were reduced to 1.4 (1.2-1.6) and 1.1 (0.9-1.3) respectively. CONCLUSION: Renal dysfunction is an important risk factor after acute myocardial infarction. When the risk is adjusted for available competing risk factors only severely reduced renal function is associated with an important and independent risk of mortality after acute myocardial infarction. The risk of a moderate reduction in renal function is almost fully explained by an association with other conditions.