Background: Prognosis and tumor responses of carboplatin-based neoadjuvant chemotherapy for muscle invasive bladder cancer (MIBC) are not well documented. To assess the usefulness of carboplatin-based neoadjuvant chemotherapy, we examined the correlation between radiological responses and pathologic down staging on radical cystectomy (RCx) specimens, disease free survival (DFS), and overall survival (OS). Methods: Between March 2005 and June 2013, we performed carboplatin-based neoadjuvant chemotherapy followed by radical cystectomy in 115 patients with T2-4NxM0 MIBC. After diagnostic TUR biopsy, all participants received two courses of Gemcitabine plus Carboplatin therapy. Baseline and post chemotherapy tumor size from contrast enhanced CT were reviewed. The patients were divided in two groups between responders (CR+PR), and non-responders (SD+PD). RCx and bilateral pelvic lymphadenectomy were performed approximately within a month after cessation of chemotherapy. DFS and OS distributions within radiologic response subgroups were estimated with the Kaplan-Meier method and compared using the log-rank test. To evaluate independent predictor for DFS and OS, age, gender, performance status, pathological T and N stage, down-staging, tumor grade, renal function, and radiological responses were applied by Cox-regression multivariate analysis. Results: No significant differences were observed in patient backgrounds between the groups. Radiologic responses were observed in 75 (65%) patients with 69±24% decrease in responder group, whereas tumor response was 2.8±14% in non-responders. The rate of pathological down staging to <pT2 was 37 (49%) in responders, 5 (13%) in non-responders group. Radiologic response was a strong predictor of DFS and OS. A 5-year advantages of DFS and OS in responders vs. non-responders were 88% and 86% vs. 64% and 69%, respectively (P=0.021 and P=0.013). Multivariate analysis showed radiologic response was the independent factor for DFS and OS. Conclusions: Radiological response post carboplatin-based neoadjuvant chemotherapy is associated with OS in patients with MIBC.