Using image cytometry and a video planimetry unit, various deoxyribonucleic acid (DNA) measurements, nuclear size and shape factors, and Gleason grade were correlated with capsular penetration, seminal vesicle invasion and lymph node involvement in 113 radical prostatectomy specimens. Percentage of nondiploid cells was the best DNA measurement and standard deviation of nuclear area was the best size measurement correlating with capsular penetration. However, stepwise regression analysis demonstrated that Gleason grade was the only independent predictor of capsular penetration. The only parameter that independently predicted seminal vesicle invasion in a stepwise regression analysis was percentage of tetraploid cells. The mode of optical density was the best DNA measurement for predicting lymph node involvement, although stepwise regression analysis found that Gleason grade was the only independent predictor. DNA ploidy was not as predictive of pathological stage. In summary, DNA measurements and nuclear morphometry performed on smears offered relatively little additional prediction of pathological stage over that of Gleason grade.