Methods of testing products made of plastics in medicine do not take into account chemico-toxicological evaluation of biomaterials made of fibres or of foam plastics. According to the project of the monograph Compendium Medicamentorum COMECON, water extracts should be used, where the is proportion would be maintained: 30 g of biomaterial in 100 cm3 of water. The proportion, in case of products with well-developed surface, does not ensure that the material is wholly immersed in fluid. Therefore studies were made on the use of lower concentration of the material in water, with on the other hand, extraction time being prolonged. Summing up, the authors suggest, with regard to grafts, use of the following conditions of water extraction: temperature 120 degrees C, duration 60 min. proportion of the studied material in the amount of distilled water 1:10.