Abstract: Soft linear thermoplastic polyurethanes, which have low permanent set, high tear propagation resistance, and low blocking, and which are extrudable by blown film techniques, are prepared by reacting one mole of a hydroxyl terminated polyester having a molecular weight from about 1800 to about 3600, from about 0.5 to about 2.0 moles of an aromatic glycol chain extender, and an organic diioscyanate in molar quantities substantially equal to the sum of the molar quantities of polyester and chain extender. The polyester is a mixed polyester prepared by reacting at least two different aliphatic glycols with one or more organic dicarboxylic acids or at least one alaphatic glycol with two or more organic dicarboxylic acids. The aliphatic glycol may have from 2 to about 10 carbon atoms. The organic dicarboxylic acid may be either aliphatic or aromatic and may have from 2 to about 12 carbon atoms. The preferred chain extender is hydroquinone bis(beta-hydroxyethyl)ether.