In a series of 94 patients with prostatic adenocarcinoma the prognostic significance of some factors was studied after radical prostatectomy. DNA ploidy was assessed by flow cytometry of cells from deparaffinized specimens. Gleason sum, seminal vesicle status and ploidy turned all out to be important predictors of disease progression. The ploidy status significantly enhanced the ability to prognostically evaluate patients with intermediate grade carcinoma compared to tumor grade alone. Patients with seminal vesicle invasion and aneuploidy had a very poor prognosis which prompts trials with alternatives of adjuvant therapy in this patient population.