Capsular margins of resection in radical prostatectomy specimens performed for carcinoma of the prostate are difficult to assess because of the scant soft tissue removed with the prostate. There is little objective information as to the validity of what are designated as positive or negative capsular margins of resection. From January 1, 1984 through June 30, 1989 there were 40 radical prostatectomies performed in which the prostate was initially removed leaving the neurovascular bundle within the patient in order to preserve potency. However, based on the surgeons' gross examination of the prostate at the time of radical prostatectomy, the neurovascular bundle was then subsequently removed during the same operation and submitted to pathology as a separate specimen. In these 40 cases the capsular margin in the region of the neurovascular bundle was assessed blindly without knowledge of tumor presence or absence in the subsequently resected neurovascular bundle, and then compared to whether the neurovascular bundle contained tumor. Of the 10 cases called positive based on review of the radical prostatectomy, only six neurovascular bundles (60%) contained tumor. Eight cases had equivocal margins with tumor extending just to the inked margin, and only one (12.5%) had tumor in the neurovascular bundle. All 20 cases with negative assigned margins had complete removal of tumor from this area with none of the neurovascular bundles containing tumor. This study demonstrated that negative capsular margins in radical prostatectomy specimens often contain only a scant amount of soft tissue. Of the 33 cases with true negative margins, the amount of soft tissue between the inked margin and tumor was only greater than 1 mm in two cases and less than or equal to 1 m in 20 cases (less than 0.5 mm in 13 cases with less than 0.25 mm in eight of these cases). Furthermore, 11 cases with tumor extending to the inked margin of resection showed no residual tumor in additional tissue removed from these regions.