The capacity of cutaneous malignant melanoma (CMM) to induce angiogenesis is well established. Tumor vascularity was compared for radial versus vertical growth phase melanomas. The radial growth phase is defined as melanoma that is predominantly intraepidermal, but usually exhibits microinvasion in papillary dermis. A necessary restriction is the absence of an expansile growth pattern in dermis. The latter feature thus signifies the vertical growth phase. In the following study, papillary dermal or tumor vascularity was quantified in 14 examples of superficial spreading melanoma (SSM) and in a series of 28 nodular melanomas (NM). We evaluated the vascularity using light microscopic evaluation of factor-VIII-immunohistochemical stained sections. Vascular density was graded and microvessels were counted per x 200 and x 400 field. The mean vascularity was recorded for three fields for each specimen. Mean vascular counts ere as follows: SMM (ą22.88) and NM (ą25.86). Although vessel counts were slightly higher in vertical growth phase versus radial growth phase melanoma, these differences were not statistically significant. There was no significant correlation between mean vessel number (MVN) and other clinico-pathological parameters which included sex, age, tumor localisation, histological type and thickness of the tumor measured by Clark and Breslow. When microvessels counts from CMM in the radial growth phase were compared with those from CMM in the vertical growth phase, or CMM5.5 mm, no significant differences were found. In conclusion, these preliminary results shows that MVN does not separate SSM from NM.