Tumor infiltrating lymphocytes (TIL) in bladder tumors have been assumed to be an expression of local host resistance against the tumor. We isolated TIL from 46 patients with transitional cell carcinoma of the bladder that were proved histopathologically. Our study patients were 33 males and 13 females, ranged in age between 24-77 years. The isolation of TIL performed by using the enzyme cocktail (Hyaluronidase and Collagenase) treatment and discontiueous gradiant centrifugation. The isolated TIL and periphral blood lymphocyte (PBL) were immunostained by the indirect immunoperoxidase method using monoclonal antibodies (CD markers): CD3 (total T-cells), CD4 (helper/inducer cells), CD8 (suppressor/cytotoxic cells) and CD2o (B-cells). Histopathologically, the patients were grouped: Group 1: grade I tumor (12) 26.1%. Group 2: grade II tumor (19) 41.3%. Group 3: grade III & IV tumor (15) 32.6%. The study showed that T-cells were the predominant cells in PBL and TIL, and tended to be higher in low-grade tumors, but decreased significantly with advancing tumor grade. The percentage of T-cell subsets decreased as the tumor grade increases. A significant reduction in their levels was found in tumor grade III & IV. This may suggest that, as the tumor becomes advanced, the mechanisms of immune escape become more powerfull in reduction of the immune response. The correlation of the T-cells between PBLs and TILs revealed that in low-grade tumors (I & II) there were a significant correlation between those cells, but as the tumor becomes of the high grade one, the correlation will be non significant. Regarding the second part of this study, which is the qualitative determination of Oncofetal Antigens (OFA) using the ELISA system, the level of Alphafetoprotein (AFP) was negative in all patients' sera. It is also noticed that there was no significant difference between the readings in the three groups of patients. Carcinoembryonic antigen (CEA) had shown to be more specific than AFP, the results revealed that 32% of the patients had positive CEA readings in their sera. This result affords no diagnostic benefit in bladder tumor, but it may be helpful in determining the progress of the disease in which most of the patients with positive CEA were of grade III & IV tumors with invasion.