Background: bladder cancer is the fourth most common cancer in males and the tenth most common cancer in females. Urinary bladder cancer occurs three to four times more frequently in men than in women and has a high recurrence rate, necessitating long-term surveillance after initial therapy. Patients with bladder cancer survive longer than those with most other common cancers. For the radiological evaluation of the urinary bladder and prostate gland, magnetic resonance imaging (MRI) is a valuable imaging modality due to high tissue contrast, multiplanar imaging capabilities, and the possibility of tissue characterization. Diffusion-weighted imaging (DWI) has emerged as a diagnostic technique in the evaluation of various abdominal lesions. Aim of the Work: to evaluate the role of diffusion weighted magnetic resonance imaging (MRI-DWI) in the diagnosis of urinary bladder carcinoma, with pathological diagnosis was taken as the reference. Patients and Methods: this is a retrospective study that included 20 patients in whom bladder cancer had been suspected either clinically or by U/S and confirmed by biopsy and 20 patients in whom bladder cancer had been not suspected and MRI was done because of other pelvic diseases as a control group. The study was conducted in El-Demerdash hospital. The patients will be referred to the radiology department from the urology department for further MRI evaluation with DWIs. Results: in this study, 20 patients suspected to have bladder cancer were scheduled for MR imaging. All patients were scheduled for different MR sequences including T2WIs, DWIs and post contrast T1WIs. Regarding the detection of urinary bladder carcinoma the sensitivity, specificity, and accuracy for differentiating superficial from invasive tumors using T2 images alone and combined use of T2 and DW images were 62.5%, 66.7%, 63.2% and 100%, 100%, 100% respectively. The sensitivity, specificity, and accuracy for differentiating superficial from invasive tumors using post contrast MR images alone and combined use of post contrast MR images and DW images were 92.3%, 100%, 93.3% and 100%, 100%, 100% respectively. Conclusion: we assume that DW-MRI is a safe and confident method in detection and local staging of urinary bladder carcinoma. In addition, DW images may predict the histological grade of the tumor. Hence DWI may be added to routine imaging protocols of urinary bladder tumors.