Tissue reaction, that is caused when polymeric materials are implanted in living tissue, is generally studied histopathologically. The histopathological evaluation is time-consuming as a first step to make an assessment of new polymeric materials. Considering that tissue reaction is usually caused by the presence of low molecular weight compounds such as various additives, monomers, impurities and degradation products of polymers, elution, hemolysis and enzymatic degradation tests were performed in vitro. And in vitro results are compared with those obtained in vivo histopathologically. Test materials were extracted in distilled water, the eluates analyzed spectrophotometrically, elution rate of leaching substances was determined and it gives a criterion of degree of tissue reaction. The repeated extraction test gave an information as to the duration or pattern of tissue reaction. The materials tested are silicone rubber, polyurethane, thermoelastic rubber, polysulfone, polyethylene carbonate. The in vitro evaluation methods studied here provided an useful information to understand the intensity, pattern or duration of tissue reaction.
