DAB2IP (DOC-2/DAB2 interactive protein) is a member of the Ras GTPase-activating protein family. It has been demonstrated to be often down-regulated and a poor prognostic factor in several human malignancies. In this study, we analyzed the clinicopathological features and outcomes of DAB2IP expression in one hundred and thirty-five patients with urothelial carcinoma of the bladder(UCB) treated by radical cystectomy(RC)plus bilateral lymph node dissection, and evaluated the effect of DAB2IP knockdown in vitro using MTT method, colony formation assay, cell cycle assay, cell migration and invasive assay. We found low expression of DAB2IP was significantly associated with high pathological stage(P=0.002), high pathological grade (P=0.02), tumor size more than 3cm (P=0.04) and presence of histological variants (P=0.01). DAB2IP was an independent prognostic factor of disease recurrence(HR:2.67;P=0.034) and cancer-specific survival (HR:2.79;P=0.038).Knockdown of DAB2IP could promote the ability of cell proliferation, migration and invasion. Down-regulation of DAB2IP could activate ERK and Akt pathway and was correlated with the expression of EMT markers, such as E-cadherin and Vimentin. In conclusion, down-regulation of DAB2IP is associated with features of biologically aggressive UCB and results in cell proliferation, migration and invasion of bladder cancer. DAB2IP may serve as a promising biomarker in patients with UCB treated by RC and bilateral lymph node dissection. This article is protected by copyright. All rights reserved.