Basal cell carcinoma (BCC) is currently the most common cutaneous cancer found in humans. Although it generally shows a relatively benign course (BCC1), some cases of BCCs show "aggressive" behavior, rapidly infiltrating deeper structures, or metastasizing (BCC2). Until now, the traditional histological diagnostic criteria have failed to discriminate unequivocally between BCC1 and BCC2. Therefore, there is still a need to find reliable prognostic indicators that correlate with outcome and may detect patients at high risk for BCC recurrence, or metastasis and death. Recent studies have suggested that there is a significant correlation between tumor angiogenesis, expressed as the microvessel density within and toward a tumor, tumor aggressiveness, and the overall survival of patients with solid tumors. In this study, the authors examined the angiogenic rate in human cutaneous BCCs, to establish if it correlates with their biological behavior. Vessels were highlighted by immunocytochemical staining for FVIII-related antigen in formalin-fixed, paraffin-embedded tissues. All BCC2 samples of this series showed a significantly higher microvessel count than did BCC1. The existence of a significant discrepancy between the neovascularization in BCC1 and BCC2 suggests that the angiogenetic process may be an important step in the acquisition of the aggressive (malignant) phenotype in human. BCCs. The findings of the present study seem to establish a correlation between tumor vascularization and clinicobiological parameters of aggressiveness in BCC. Considering the emerging studies on the possible clinical use of substances interfering with the angiogenetic process, it is possible that the local therapy for BCCs could become less destructive, with consequent improvement in the quality of life of these patients, apart from the prolongation of the overall survival. From this view-point, the assay of microvessel density might be helpful in selecting patients with cutaneous BCCs at high risk for recurrence or metastasis, who could benefit ab initio from additional therapies and closer follow-up.