The aim of this work was to assess the presently used prognostic indicators in bladder carcinoma and also to test the prognostic value of two markers, i.e. ABH isoantigen reactivity and DNA ploidy, after methodological improvements. The study comprised all patients with newly diagnosed bladder tumors seen at Uppsala University Hospital in 1975-1978. The observation time was 5 to 9 years, averaging 6.5 years. No patient was lost to follow-up. Of the 230 transitional cell carcinomas, 66% were superficial (Tis, Ta, T1), 31% were muscle-invasive (T2, T3, T4), and six could not be staged (Tx). Primary treatment was mainly transurethral resection for superficial tumors, but was cystectomy or radiotherapy in 22 of 29 T1 G3 cases. Of the patients with superficial tumors 71% had recurrence. Progression to a higher T category occurred in 15% of Ta and 29% of T1 tumors, and half of these patients died of the disease despite close follow-up. The corrected 5-year survival rates in grades 1, 2A, 2B and 3-4 were 96, 84, 64 and 43%, and in stages Ta, T1, T2 and T3 they were 94, 69, 40 and 31%. All patients with a T4 tumor died within 4 years. Forty-five patients (20%) died of intercurrent disease. A highly standardized, semiquantitative method to determine ABH blood group isoantigens, using the avidin-biotin-peroxidase complex technique, was developed. The DNA content of the primary tumor was determined by flow cytometry on material obtained from paraffin blocks. An improved method for this analysis was elaborated, based on proteolytic digestion with protease and density separation of the nuclei by Percoll centrifugation. In 195 cases it was possible to assess the DNA ploidy and the ABH reactivity in the primary biopsy. Aneuploidy and ABH negativity were noted in 39% of the cases, mainly high grade high stage tumors. ABH positive tumors were usually diploid, but ABH negative ones were more evenly aneuploid or diploid. Early progression (first 36 months) occurred in 2% of patients with diploid ABH positive tumors and in 31% of those with aneuploid ABH negative tumors (p less than 0.008). The corrected five-year survivals were 95% and 56% respectively (p less than 0.0001).(ABSTRACT TRUNCATED AT 400 WORDS)