DNA-ploidy in 143 cases of prostatic carcinoma was assessed by flow cytometric analysis of paraffin-embedded biopsy material. The majority of the tumours (64.3%) were diploid, but in advanced stages the DNA-aneuploidy rate increased from 15 to over 60%. No hypoploid tumour was observed and most of the hyperploid tumours were near-tetraploid. DNA-aneuploidy was also strongly related to histological grade. Survival analysis using Cox multivariate regression model revealed that low histological grade (high Gleason score), advanced stage and increased level of prostatic acid phosphatase were the most important prognostic factors. DNA-ploidy per se did not contribute independently as a predictor of survival.