OBJECTIVES: To estimate hospital costs and charges attributable to the development of acute renal insufficiency (ARI) and acute renal failure (ARF) after coronary artery bypass grafting (CABG). METHODS: A retrospective analysis of patients undergoing CABG at University of Pittsburgh Medical Center from June 1998 through May 2002 was conducted. Patients were matched with respect to severity of illness by APACHE III scores. A Wilcoxon signed-rank test was used to assess differences in costs and charges. RESULTS: There were 3741 total patients that resulted in 644 matched pairs. The mean and median hospital charges among cases were approximately $221,864 and $158,312 respectively. The mean and median hospital charges among controls were approximately $110,868 and $91,738 respectively. Distribution of the hospital charges were positively skewed (Shapiro-Wilk test, 0<0.001). The difference in median hospital charges was $66,500 (Wilcoxon signed-rank test, p<0.01). The mean and median hospital costs among cases were $44,180 and $28,901 respectively. The mean and median hospital costs among controls were $22,471 and $18,038 respectively. The difference in median hospital costs was $10,863 (Wilcoxon signed-rank test, p<0.01). The mean and median ICU costs among cases were $35,566 and $21,183 respectively. The mean and median ICU costs among controls were $17,634 and $13,655 respectively. The difference in median ICU costs was $7528 (Wilcoxon signed-rank test, p<0.01). CONCLUSIONS: Although patients were matched using APACHE III scores, a severity of illness scoring system, patients with ARI/ARF after CABG had significantly higher hospital and ICU costs and charges than patients without ARI/ARF. These differences can be attributed to the development of renal complications after CABG.