The association between microvessel density (MVD) and patient survival has recently been established for various types of human cancers. Immunohistochemical staining (factor-VIII related antigen) was performed on a series of 102 vertical growth phase melanomas and vessels were counted in <hot spot> areas. Increased MVD was associated with large histologic tumor diameter (p=0.006) and tumor ulceration (p=0.04). Further, high vascular density was significantly related to decreased patient survival (p=0.04), with borderline significance (p=0.10) in the final multivariate model. The results of this study suggest that microvessel density is of prognostic importance in aggressive vertical growth phase melanomas.