Few studies have investigated the prognostic value of a variety of cell-biological parameters in cases of urachal adenocarcinoma, a rare neoplasm. The authors examined three cell-biological parameters--DNA status, proliferating cell-nuclear antigen (PCNA) immunostaining, and argyrophilic nucleolar-organizer region (AgNOR) counts--in surgically resected, formalin-fixed, paraffin-embedded urachal adenocarcinomas from 41 patients. The authors quantified DNA distribution in 200 cancer cells from a section of each tumor, stained with 4',6-diamidino-2-phenylindole, using a microspectrophotometer. The authors also measured the number of PCNA immunostaining cells in 1,000 nuclei, and AgNORs counts in 200 nuclei, from sections of each tumor. There were eight specimens with group 1 DNA distribution (defined as a DNA content of under 4c in >90% of the cells), 21 of group 2 DNA distribution (more than 4c in >10% of the cells and more than 6c in <10% of the cells), and 12 of group 3 DNA distribution (more than 6c in >10% of the cells). The percentage of PCNA-positive cells was 19% to 91% (median, 59.5%), and the mean AgNOR count was 2.2 to 8.8 (median, 5.3) granules per nucleus. The 5-year survival rate for all 41 patients was 50.2%. Initial univariate analyses indicated that tumor stage, histological differentiation, and DNA status had a significant effect on survival. In the final models using multivariate analysis, only tumor stage and histological differentiation were found to be prognostic factors. These investigations confirm the vital importance of tumor stage and histological differentiation as predictors of patient survival. The three cell-biological parameters the authors studied do not appear to be important parameters for predicting survival.