Objective: To study the histomorphological pattern of urothelial tumors of the urinary bladder in Manipur and to evaluate whether any correlation exists between tumor grade and muscle invasion. Methods: A 10 year retrospective study of all consecutive cases diagnosed in the Department of Pathology RIMS - Imphal, between $1^{st}$ January 2001 to $31^{st}$ December 2010. Results: The study included 26 cases of transitional cell tumors of urinary bladder. The male to female ratio was 1.5:1 and the ages ranged from 38 years to 73 years (medians of 60 and 64 years, respectively). Of the total, 14 (53.9%) cases were low grade, 9 (34.6%) were high grade, 2 (7.7%) were papillomas and 1 (3.9%) was a papillary urothelial neoplasm of low malignant potential (PUNLMP). Pathological staging showed that 14 (53.9%) of the cases were stage PTa, four (15.4%) PT1, and eight (30.9%) PT2. Some 18.2% of low grade tumors and 75% of high grade tumors were invasive to the detrusor muscle layer. Conclusion: Bladder cancer is an uncommon disease, transitional tumors being the only histological type observed. It was more common in males than females, with peak incidence in seventh decade. Most of the tumors were non-invasive (PTa) and invasion to the detrusor muscle layer was seen in more than half of the high grade tumors. There is a definite correlation between advancing tumor grade and muscle invasion.