The aim of the present study was to analyze the influence of different preconditioning treatments with either bovine serum albumin or cell culture medium of different dental metal alloys on human fibroblast cultures in the presence of such biomaterials as regards both cell proliferation rates and the expression of molecules constituting the extracellular matrix. Human fibroblasts (cell line Flow 2002) were cultured for 72 h in the presence of six single-phase dental casting alloys. The amount of Ag+ and Cu++ release into cell culture media was measured by atomic absorption spectroscopy. Incorporation of 5-bromodeoxyuridine, to investigate cell cycle, and the expression of fibronectin and chondroitin sulfate glycosaminoglycans, to evaluate cell adhesion, were analyzed with an immunocytochemical approach and related to cytocompatibility of the different substrates. The immunocytochemical analysis were performed by fluorescence microscopy and further analyzed with an image analysis software. Preconditioning treatments for 72 h induced decreasing cytotoxicity of the tested alloys: indeed metal cation concentrations decreased in cell culture media in the presence of preconditioned dental metal alloys. Both cell proliferation rates and ECM-constituting molecule expression resulted higher when tested in the presence of preconditioned dental metal alloys. Therefore, it is reasonable that preconditioning treatments of dental alloys influenced their interactions with fibroblast cultures by increasing their cytocompatibility in vitro. (c) 2005 Springer Science + Business Media, Inc.