BACKGROUND: [corrected] The purpose of this study was to explore whether changes in matrix metalloproteinase-9 (MMP-9) are involved in the progression of urinary bladder cancer and whether they have any prognostic value. PATIENTS AND METHODS: Overexpression of MMP-9 was evaluated in the primary tumor of 87 urinary bladder cancer cases with immunohistochemical staining. RESULTS: Of the urinary bladder carcinomas, 38% showed an overexpression (>25%) of MMP-9 immunoreactive protein. Increased positivity for MMP-9 correlated with favorable overall survival of the urinary bladder cancer patients. The 5-year overall survival and relapse-free survival was 68% and 36% in patients showing high MMP-9 expression and 48% and 19% in patients with low (<25%) or negative MMP-9 expression (p=0.006, p=0.08, respectively). In multivariate analysis, MMP-9 overexpression seems to retain its independent prognostic value. CONCLUSION: This study shows that MMP-9 expression in urinary bladder carcinoma is associated with better prognosis.