With the purpose of diffuse membranous oxygenation of blood the possibility of employing a Soviet-made dimethylpolyxyloxane-reinforced film "Sigma" was investigated. The test-trials were carried out with a membranous oxygenator of the "Sandwich" type. In 15 acute tests on dogs a partial cardio-pulmonary pass-by shunting with oxygenation of the blood after the veno-venous or veno-arterial perfusion was performed. With the mass-exchange area of 1.15 m2 the oxygen transport in different tests varied within a range of 20-50 ml/min and depended upon the arterio-venous difference and the circulation rate. No disruptions in the elimination of carbon dioxide were in evidence. In the course of investigations the "Sigma" material was found to be strong, impermeable to liquids and is not subject to swelling following its long-term use.