Transitional carcinoma of the bladder, an important tumor in both men and women, has traditionally been diagnosed and monitored using either or both of two different methodologies. Urinary cytology is highly specific, but has poor sensitivity. Cystoscopy with biopsy is highly accurate, but invasive. A newly developed immuno cytochemical test, ImmunoCyt trade mark (DiagnoCure Inc.), uses three monoclonal antibodies directed against transitional cell carcinoma antigens in exfoliated cells. This study involved 102 asymptomatic controls, and 198 patients with confirmed bladder cancer, in an assessment of the performance characteristics of ImmunoCyt. Combining this test with conventional urinary cytology improves accuracy. Depending on the cutoff level used in the interpretation of a positive result, the highest sensitivity of the test was 95%, with a corresponding specificity of 76.5%. This procedure offers the possibility of non-invasive diagnosis and monitoring of bladder cancer, with acceptable performance characteristics.