In this study, interactions of widely-used polymeric biomaterials, i.e. poly(hydroxyethyl methacrylate) (PHEMA) and its copolymer with dimethylaminoethyl methacrylate (PHEMA-20% DMAEMA), polyurethane (PU), polypropylene (PP), poly(vinyl chloride) (PVC), and poly(lactide-glycolide) (PLGA), with three pathogenic bacteria and one nonpathogen were investigated comparatively with the adhesion of two tissue cells in different morphologies, i.e. fibroblast-like baby hamster kidney (BHK 21) cells and epithelial Madine Darby kidney (MDBK) cells. Biomaterials were prepared in the membrane form by bulk polymerization or solvent casting. Surface characterization studies showed that these polymers have different surface free energies in the range of 26.9-63.1 erg cm-2 and they have smooth surfaces. The bacteria used were; Escherichia coli ATCC 25922, Staphylococcus epidermidis ATCC 12228, Staphylococcus aureus, and Lactobacillus acidophilus B-13. Initial adhesion of bacteria to the polymeric surfaces was examined under static conditions and in a laminar flow cell. The adhesion behaviour of S. aureus and S. epidermidis was found independent of the polymeric surface hydrophobicity. However, the percentage of attached E. coli decreased when increasing the surface free energy of the polymer, while L. acidophilus showed just the opposite behaviour. The comparative results indicated that the adhesion of BHK and MDBK cell was lowest on the most hydrophilic PHEMA surface and highest on the most hydrophobic PP surface. In contrast to the case of bacterial adhesion, no relationship was found between polymer hydrophobicity and mammalian cell adherence.