Clinical and histological prognostic factors were evaluated by means of Cox's analysis in 265 bladder cancer patients with a mean followup of 10 years. The parameters studied were obtained from the primary biopsies, which included clinical stage, World Health Organization grade, papillary status, morphometrically measured mean nuclear area, standard deviation of nuclear area, mean nuclear area of the 10 largest nuclei, mitotic activity index and volume corrected mitotic index. In univariate survival analysis all of the parameters predicted survival (p less than 0.001). In Cox's analysis the clinical stage was the most important prognosticator (p less than 0.001) followed by papillary status (p less than 0.001), volume corrected mitotic index (p = 0.011) and nuclear area of the 10 largest nuclei (p = 0.091). In stages Ta to T2, grades 1 to 2 tumors the papillary status (p = 0.001), mitotic activity index (p = 0.021) and T category (p = 0.029) showed independent prognostic value. Among the stages Ta to T1 tumors the papillary status included all of the available prognostic information (p = 0.001). In a separate analysis of histological features in all papillary tumors histological grade (p less than 0.001) and mitotic activity index (p = 0.021) were related independently to survival in Cox's analysis. In papillary stages Ta to T2, grades 1 to 2 tumors (mitotic activity index, p = 0.029) and in papillary stages Ta to T1 tumors (volume corrected mitotic index, p = 0.054) mitotic indexes showed independent prognostic value. In grade 2 tumors the papillary status p = 0.004) and mitotic activity index (p = 0.090) had independent prognostic value. The mitotic indexes predicted progression among stages Ta to T1 tumors (p less than 0.001) and within World Health Organization grades significantly. The combination of prognostic parameters into prognostic scores gave a more accurate estimate of survival than the single parameter approach. The results suggest morphometric grading of bladder tumors. However, papillary and nonpapillary tumors require different grade limits.