We investigated the immunoreactivity for bcl-2 oncoprotein in 154 cases of transitional cell carcinoma of the upper urinary tract (TCC-UUT) and its relation with the immunoreactivity for p53 oncoprotein and proliferating cell nuclear antigen (PCNA) immunoreactivity. Immunohistochemically, bcl-2 oncoprotein was recognized as positive in 29.2% of the samples. The immunoreactivity for bcl-2 oncoprotein was significantly (P < 0.05) correlated only with stage, though there was a borderline correlation (P = 0.050) with PCNA immunoreactivity. Furthermore, in invasive TCC the immunoreactivity for bcl-2 oncoprotein was associated with PCNA immunoreactivity (P < 0.041). The 5-year disease-free and overall survival rates were 55.7% and 71.5%, respectively. A univariate analysis of survival revealed that stage, grade, pattern of growth, immunoreactivity for p53 oncoprotein, and PCNA immunoreactivity each had a significant effect on disease-free and overall survival rates, whereas the immunoreactivity for bcl-2 oncoprotein had no significant effect on either rate. In the final models of the multivariate analysis, stage was found to be the only prognostic factor for disease-free survival and for overall survival. Detection of immunoreactivity for bcl-2 oncoprotein appears to be of no real value in deciding the prognosis of TCC-UUT.