In order to investigate how cells recognize biomaterials, mRNA that was expressed in attached HeLa S3 cells on various substrates was evaluated. As culture substrates, cellulose, ethylene-vinyl alcohol copolymer (EVAL), nylon, tissue culture polystyrene (TCPS), high-density polyethylene (PE), silicone rubber, and tetrafluoroethylene-hexafluoropropylene copolymer (6F) were used. HeLa S3 cells were cultured on these substrates for 24 h. The expressed HSP 70s mRNA was then isolated and detected using the RT-PCR method. As a result, the expression of HSP 70B mRNA was largely induced in cells that adhered to hydrophilic surfaces. On the other hand, on hydrophobic surfaces, the HSP 70B mRNA expression was low. It is concluded that HSP 70B mRNA expression is sensitive to differences in the hydrophilicity-hydrophobicity of the substrates.