Background: Parafibromin is a recently defined tumor suppressor gene. The aim of our study was to determine the relationships of parafibromin expression in urothelial carcinomas (UCs) with prognostic parameters and to evaluate the use of parafibromin as a potential marker of UC. Methods: Parafibromin expression was assessed in 49 UC specimens using immunohistochemistry. The correlations between parafibromin expression and clinical and pathologic parameters were investigated. Results: Of the patients, 42 (85.7%) were male, and the mean age was 69.6 +/- 8.2 years (range, 54 to 88 years). Morphologically, the UCs were divided into two groups: papillary (n = 27) and non-papillary (n = 22). There were seven low-grade (14.3%) and 42 high-grade (85.7%) tumors. Parafibromin was negative in 13 tumors (26.5%), partially positive in 19 tumors (38.8%), and positive in 17 tumors (34.7%). Parafibromin expression was more negative in UCs from upper urinary locations (n = 17) and with muscularis propria invasion (n = 28), which was statistically significant (p = .009 and p = .007, respectively). There was no statistically significant relationship between parafibromin expression and gender, age, tumor grade, survival, or disease-free survival. Conclusions: We found that UC cases with parafibromin positivity had less of a tendency to show muscularis propria invasion and were more commonly located in the lower urinary system. These results need to be confirmed with studies based on larger case series.