The aim of this study was to elucidate the associations between immunostaining for MDM2 and p53, their respective expression in squamous cell carcinoma of the urinary bladder, and the value of these variables for predicting treatment outcome after cystectomy. Inactivation of TP53 might play a role in the development and progression of bladder cancer. Complex formation with the MDM2 product is one mechanism that inactivates the p53 protein. Therefore, the MDM2 and the p53 protein were investigated to study potential interactions in bladder cancer. Fifty archival bladder tissue specimens were immunohistochemically stained using monoclonal antibodies against p53 and MDM2. Staining for p53 was observed in 48% of the specimens and staining for MDM2 in 20%. Univariate analysis demonstrated a significant correlation between p53 accumulation and survival (p = 0.0101), while the correlation between MDM2 and survival was not significant (p = 0.7183). The combined expression of MDM2 and p53 doest not add to the prognostic information provided by p53 alone.