The biological potential of prostate cancer is highly variable and cannot be satisfactorily predicted by histopathological criteria alone. Angiogenesis, the formation of new blood vessels, has been suggested to provide important prognostic information in prostate cancer. The aim of this study was to investigate whether microvessel density (MVD) at diagnosis was correlated with disease-specific survival in a non-curative treated population of prostate cancer patients. MVD was immunohistochemically (factor VIII-related antigen) quantified in archival tumours obtained at diagnosis in 221 prostate cancer patients. Median length of follow-up was 15 years. The maximal MVD was quantified inside a 0.25 mm2 area of the tumour and the median MVD was 43 (range 16-151) mm2. MVD was statistically significantly correlated with clinical stage (P < 0.0001) and histopathological grade (P < 0.0001). When dichotomized by the median counts, MVD was shown to be significantly associated (P = 0.0001) with disease-specific survival in the entire population as well as in the theoretically curable clinically localized subpopulation. A multivariate analysis demonstrated that MVD was a significant predictor of disease-specific survival in the entire cancer population (P = 0.0004), as well as in the clinically localized cancer population (P < 0.0001). These findings suggest that quantitation of angiogenesis reflects the spontaneous clinical outcome of prostate cancer.