Prostatic carcinoma obtained from 41 patients (pT2N0, 5; pT2N+, 2; pT3N0, 16; pT3N+, 16; pT4N0, 1; and pT4N+, 1) ranging from 45 to 79 years of age were investigated in the present study. A total of 410 tumor areas of different grades were analyzed (G1, n = 116; G2, n = 98; and G3, n = 196). Vascular structures were labeled immunohistochemically using factor-VIII-associated antigen. The vascular surface density (VSD), the microvessel number (NVES), and the maximum microvessel number (NVES-MAX) were assessed by means of stereology, and the results were related to tumor stage, nodal status, and grade of differentiation. NVES and NVES-MAX showed a significant increase with rising pT stage ranging from 25.5 +/- 1.48 in controls to 135.0 +/- 5.5 microvessels/mm2 in pT4 tumors. Discrimination of different pT stages was more accurate with NVES-MAX. The VSD was significantly higher in pT2 tumors compared with controls, whereas there were no significant differences between pT3 tumors, pT4 tumors, and controls, although the values in pT3 and pT4 tumors were distinctly lower than in pT2 tumors (P < .05). The VSD and the NVES were not able to discriminate between the pN0 and the pN+ group. Both parameters were slightly higher in patients with metastatic disease. Only NVES-MAX values differed between the two groups with an average of additional 21 microvessels/mm2 in the pN+ group (P < .05). Concerning the grade of tumor differentiation the VSD continuously decreased from G1 (14.58 +/- 2.24 mm(-1) to G3 tumor areas (5.41 +/- 1.46 mm(-1). Only G1 tumors showed significant differences compared with controls (6.65 +/- 0.38 mm(-1). The NVES increased with rising tumor grade with significant differences between all four groups ranging from 25.5 +/- 1.5 in controls to 136.9 +/- 37.2 microvessels/mm2 in pT4 tumors.