Purpose: The aims of this study were to investigate the clinical value of Rab27a as a urinary biomarker, and its efficiency in the prediction of bladder cancer grade.Materials and Methods: The expression of Rab27a in urine samples of patients with bladder cancer, cell line (T-24), and tissue samples of patients with bladder cancer was estimated via quantitative reverse transcription polymerase chain reaction (qRT-PCR). The Rab27a expression level was investigated according to sex, age, and histological grade via qRT-PCR and Western blotting.Results: Rab27a was also expressed at high levels in urine compared to cell lines and tissues from bladder cancer patients. In addition, Rab27a expression varied significantly according to tumor grade (p<0.001). Rab27a was expressed at high levels in male and elderly patients, however, there was not statistically significant.Conclusions: Our results indicated that Rab27a is valuable as a urinary diagnostic biomarker for bladder cancer. In addition, it may serve as a predictive factor for determining bladder cancer grade.