A new technique has been developed that helped in an accurate prediction of the prognosis of 27 patients with stages B1 and B2 prostatic cancer following radical prostatectomy. This method involves computer-assisted image analysis of histological specimens of the primary lesion removed at the time of radical perineal prostatectomy. On the basis of a nuclear shape factor, known as nuclear roundness, we have been able to distinguish those tumors with a high metastatic potential from tumors that are less aggressive. This technique provides pathologists with quantitative information about the metastatic potential of a tumor, which may aid in the management of the individual patient.