Purpose: To evaluate and compare the functional outcomes of ileal and sigmoid neobladders in patients underwent radical cystectomy. Methods: Relevant studies were identified by searching PubMed, Embase, and Cochrane Library. The studies comparing the functional outcomes of sigmoid neobladder (SN) and ileal neobladder (IN) in patients underwent radical cystectomy were included. Results: A total of 12 cohort studies were included in this meta-analysis. From our analysis, more early complications were observed in SN group than in IN group (RR = 1.37, 95% CI: 1.03-1.81). Both daytime and nighttime continence rates were significantly better in IN group than in SN group (RR = 0.87, 95% CI: 0.81-0.94) (RR = 0.73, 95% CI: 0.60-0.90). More patients could spontaneous voiding in SN group than in IN group (RR = 1.12, 95% CI: 1.00-1.26). According to the urodynamic study, ileal neobladder exhibited bigger capacity (WMD = -84.93, 95% CI: = 160.36 to -9.50), lower pressure at capacity (WMD = 11.18, 95% CI: 4.29-18.06), better compliance (WMD = -25.55, 95% CI: -32.45 to -18.64), and greater post-void residual volume(WMD = -23.48, 95% CI: -36.75 to -10.21); There was no significant difference in the max voiding flow rate or void volume between the two groups (WMD = -1.00, 95% CI: -3.73-1.73) (WMD = -27.00, 95% CI: 70.05-16.06). No significant difference was found in the serum creatinine between the two groups (WMD = -0.05, 95% CI: -0.12-0.03). Conclusions: Ileal neobladder seems able to provide more favorable patient's satisfaction, while sigmoid neobladder may provide a better chance of spontaneous voiding. This meta-analysis may provide some useful evidences for urological surgeons to choose the ideal bladder substitute for patients underwent radical cystectomy. (C) 2016 IJS Publishing Group Limited. Published by Elsevier Ltd. All rights reserved.