The expression of alpha 5 beta 1 (alpha 5 beta 1) integrin and its extracellular ligand fibronectin was studied immunohistochemically in 23 cases of Dupuytren's disease using an immunoperoxidase method for light microscopic visualization. All cases consisted of multiple nodules showing a variable degree of cellularity and fibrosis. Depending on the histological appearance of these nodules, each case was assigned to the three following phases: proliferative, involutional and residual. Alpha 5 beta 1 integrin was detected in the highly cellular areas of both proliferative and involutional phases where fibronectin was simultaneously expressed in the extracellular matrix (ECM). Diversely alpha 5 beta 1 and fibronectin disappeared from the hypocellular areas of involutional phase, undergoing fibrotic transformation, and from the fibrotic connective tissue of residual phases. These findings indicate that the expression pattern of alpha 5 beta 1 integrin correlates with the presence in the ECM of the corresponding ligand fibronectin during the different phases of Dupuytren's disease. We suggest that alpha 5 beta 1 integrin, linking fibronectin to stromal cells of both proliferative and involutional phases, may be involved in the contractile processes occurring in Dupuytren's disease.