Although dental implants have undergone impressive evolution in recent years, periimplantitis still remains a relevant problem and information on the susceptibility of commercial implants to bacterial colonization is insufficient. This work evaluated the susceptibility of different commercial implants to bacterial colonization, to identify key features for good performances. Twenty-four implants, produced with different technologies, were colonized with 9 bacterial strains following pre-conditioning with culture medium, or saliva or serum proteins and adherent bacteria were enumerated by Real Time quantitative PCR. The studied implants differed significantly for susceptibility to bacterial adhesion. Pre-conditioning of surfaces affected adhesion assays in a species specific manner. Although surface topography influenced bacterial adhesiveness, implants produced by different manufacturers with comparable technologies showed great variability of results. These data demonstrate that susceptibility of implants to bacterial colonization is influenced by productive technologies (in a surface topography proportional manner) and by the productive environment. In choosing an implant the clinician should rely upon specific experimental studies, because surface characteristics alone cannot predict susceptibility to colonization by pathogenic bacteria. Tests should include assays performed in the medium of culture and in the presence of serum proteins.