A retrospective study was performed on 83 bladder cancer patients diagnosed at the Department of Surgery, Kuopio University Central Hospital, during the years 1965-1987. The follow-up time was 22 years, and the mean follow-up time of individual patients was 13 years (range 9.4-22 years). Histological grade (WHO), volume corrected mitotic index (M/V index) and clinical stage (UICC) were correlated to the survival of patients. Histological grade, M/V index and clinical stage were associated with crude survival (all causes of death included) with little predictive power. The recurrence of the disease could be predicted by the M/V index, but not by histological grade or clinical stage. When bladder cancer deaths only were included, histological grade (chi 2 = 26.6, p less than 0.001), M/V index (chi 2 = 6.6, p = 0.042) and clinical stage (chi 2 = 31.7, p less than 0.001) were clearly associated with prognosis. Also the metastasizing potential of bladder carcinomas could be predicted by the M/V index and by the histological grade at the time of primary diagnosis. Histological grade and M/V index were positively correlated (chi 2 = 16.7, p = 0.002, r = 0.47). In multivariate analysis clinical stage, histological grade and M/V index predicted prognosis in the order of importance.