Renal dysfunction is a significant risk factor in the prognosis of patients with cardiovascular diseases. We sought to determine the relationship between estimated glomerular filtration rate (eGFR) values and in-hospital mortality in Japanese acute myocardial infarction (AMI) patients. A total of 2266 consecutive AMI patients admitted to 22 hospitals in Hokkaido were registered. The eGFR values were determined using the following equation: eGFR=194 × (serum creatinine)(-1.094) × (age)(-0.287) ( × 0.739 if female). Patients were classified into four groups according to their eGFR values: ≥60 (n=1304), 30-59 (n=810), 15-29 (n=87) and <15 ml min(-1) per 1.73 m(2) (n=65). A total of 110 patients (4.9%) died during hospitalization. The in-hospital mortality rate was significantly higher in patients with reduced eGFR values at 2.3, 5.4, 24.1 and 23.1% for eGFR values of ≥60, 30-59, 15-29, and <15 ml min(-1) per 1.73 m(2), respectively. The odds ratios for in-hospital all cause death were 8.26 (95% confidence interval (CI): 2.22-30.77) for eGFR<15 ml min(-1) per 1.73 m(2) and 3.42 (95% CI: 1.01-11.61) for eGFR 15-29 ml min(-1) per 1.73 m(2) compared with eGFR ≥60 ml min(-1) per 1.73 m(2). Similarly, the odds ratios for in-hospital cardiac death were 8.43 (95% CI: 1.82-39.05) for eGFR<15 ml min(-1) per 1.73 m(2) and 5.47 (95% CI: 1.51-19.80) for eGFR 15-29 ml min(-1) per 1.73 m(2). In conclusion, the eGFR of <30 ml min(-1) per 1.73 m(2) was a significant and independent risk for in-hospital mortality in abroad cohort of Japanese patients with AMI.