BACKGROUND Tumor angiogenesis is necessary for tumor growth and metastasis, and increasing intratumoral microvessel density (MVD) in prostate carcinoma has been shown in several studies to be associated with increasing tumor stage. But, the relationships of endothelial cell proliferation to intratumoral MVD, tumor cell proliferation, and Gleason's score remain unknown in prostate carcinoma. METHODS Using a double-immunolabeling technique (paraffin-reactive MIB1 Ab to determine Ki67 labeling index (Ki67LI) and anti-CD34 to quantify microvessels), we immunostained 20 prostatic carcinomas and adjacent benign prostate hyperplasia (BH) and four cases of trauma-induced granulation tissue. We correlated intratumoral endothelial cell proliferation with intratumoral MVD, tumor cell proliferation, and Gleason's score, and we compared these measurements with endothelial cell proliferation, MVD, and epithelial cell proliferation in adjacent BH. RESULTS The intratumoral endothelial cell proliferation index (mean 0.15%) and intratumoral MVD measured 30-fold (p = 0.00007) and 1.9-fold (p = 0.000003) greater than that of adjacent BH, respectively. However, the intratumoral endothelial cell proliferation index did not correlate with intratumoral MVD, tumor cell proliferation, or Gleason's score. Nor did intratumoral MVD correlate with tumor cell proliferation. In comparison, the mean MVD and endothelial cell proliferation rates in granulation tissue were 199 and 6.50%, respectively, the latter 43-fold greater than the mean intratumoral endothelial cell proliferation index (p = 0.00023). CONCLUSIONS Endothelial cells are actively proliferating in prostatic carcinoma, and their proliferation appears independent of intratumoral MVD and tumor cell proliferation. Yet, the relatively low intratumoral hyperplasia, suggests that endothelial cell migration and capillary remodeling play an important role in neovascularization of prostatic carcinoma, especially when compared with granulation tissue, which showed a 43-fold greater endothelial cell proliferation index. Moreover, the lack of correlation of intratumoral endothelial cell proliferation and intratumoral MVD with tumor cell proliferation suggests that tumor angiogenesis and tumor-cell proliferation are regulated by different mechanisms.