Assessment of renal function is important to determine the appropriate dose for cisplatin (CDDP)-based chemotherapy. Many previous CDDP-based chemotherapy trials for bladder cancer have required a creatinine-clearance (Ccr) ≧60 ml/min for entry. However, there is little evidence on renal function assessed by estimated glomerular filtration rate (eGFR) using the 4-variable Modification of Diet in Renal Disease Study Equation (MDRD), which has recently been introduced, to determine the eligibility for CDDP-based chemotherapy. To evaluate the proportion of patients with invasive urothelial carcinoma(UC) who would be ineligible ("unfit") to receive CDDP-based chemotherapy based on eGFR criteria (eGFR ＜60 ml/min/1.73 m2), and to determine the side effects of chemotherapy in these "unfit" patients, we conducted a retrospective clinical study. Our study population consisted of 61 consecutive patients who underwent 100% dose CDDP-based chemotherapy for invasive UC with 24 h-Ccr≧50 ml/min between June 2001 and July 2009. We assessed renal function using 3 equations (eGFR, Ccr according to Cockcroft-Gault formula (C-G Ccr), and Ccr examined by 24-hour urine collection (24 h-Ccr)) as well. Mean values of eGFR, C-G Ccr, and 24 h-Ccr were 58.6, 68.9, and 82.8 ml/min, respectively (P＜ 0.001). In total, 29/61(48%) patients were ineligible ("unfit") to receive chemotherapy based on eGFR criteria. However, there was no difference in the frequency of side effects between eGFR ≧60 ml/min/ 1.73 m2 and eGFR ＜60 ml/min/1.73 m2 groups. Our observations suggest that 24 h-Ccr≧50 ml/min would be a reasonable cutoff for CDDP-based chemotherapy even when eGFR ＜60 ml/min/1.73 m2.