The cell-surface heterodimers of the integrin family of molecules, which mediate cell-cell and cell-substratum interactions, are likely to be functionally relevant in local and metastatic tumor growth. In the present study we have analyzed whether the alpha 3/beta 1 receptor for collagen, laminin and fibronectin undergoes changes in expression during tumor progression in cutaneous malignant melanoma (CMM). The results of this study have demonstrated that, while low levels of VLA3 expression are detectable in benign lesions, in primary melanomas the heterodimer undergoes progressive increase in expression which correlates with the degree of dermal invasiveness. Metastatic lesions were found VLA3 positive in 82% of cases. Furthermore, the heterodimer is homogeneously expressed in multiple autologous metastases. The presence of VLA3 correlates with detection of at least one of the ligands in 45% of the cases studied. These findings provide additional evidence that tumor progression in CMM is associated with changes in integrin phenotypes which include the alpha 3/beta 1 heterodimer.