BACKGROUND Renal insufficiency is common in patients with chronic heart failure (CHF), so to improve the prognosis of patients with cardiovascular risks clinical guidelines recommend estimating the glomerular filtration rate (GFR), which detects chronic kidney disease more accurately than does the serum creatinine level alone. However, the clinical usefulness of the estimated GFR (eGFR) in Japanese CHF patients is still unclear. RESULTS Of 1,278 patients registered in a Japanese CHF registry, termed the Chronic Heart Failure Analysis and Registry in the Tohoku District study, the study population included 920 symptomatic patients with sufficient data. Baseline eGFR (ml .min(-1) . 1.73 m(-2)) was calculated using the Cockcroft-Gault equation. Patients were divided into three groups based on eGFR: > or =60, 30-59, and <30 ml . min(-1) .1.73 m(-2). Kaplan-Meier analysis revealed that the incidence of the combined event of all-cause death and admission because of CHF was significantly higher in patients with reduced eGFR and such patients were older and more frequently had an ischemic etiology of CHF, a higher prevalence of diabetes, lower hemoglobin level, and higher B-type natriuretic peptide level. Multivariate Cox regression analysis showed that reduced eGFR was significantly associated with the combined endpoint. CONCLUSIONS GFR should be evaluated in all Japanese patients with CHF to improve risk stratification and treatment.