Malignant melanoma usually progresses from the intraepidermal microenvironment through a distinct radial growth phase, in which malignant potential cannot always be accurately evaluated, to invasion of the dermis (vertical growth phase) and metastasis. During these stages malignant cells interact with each other and with the extracellular matrix. This interaction is mediated by cell surface adhesion molecules such as the β3 integrin subunit and ICAM-1. Our aim was to investigate whether the expression of these two molecules is associated with the various histopathologic prognosticators commonly evaluated in malignant melanoma. Using a standard three-step immunoperoxidase technique we evaluated the above molecules' expression in a documented series of 66 cutaneous malignant melanomas. Forty-five were superficial spreading melanomas, including 18 in mixed growth phase. Positive immunoreaction was estimated by image analysis. ICAM-1 immunopositivity status was significantly more frequent among malignant melanomas of the nodular type (p=0.0001), and was associated with the vertical growth phase, Breslow thickness of >0.77 mm, and with evident lymphocytic infiltration. β3 integrin immunopositivity showed similar results in certain respects; it was more frequently detected in superficial spreading melanomas in which vertical growth had developed (p=0.002) and in cases with regression. There appears to be an association of these molecules with histopathologic features that predict increased tumorigenicity of malignant melanocytes.