Abstract: Method for manufacturing polyurethane films and surface coatings from tall oil pitch. Tall oil pitch with an acid number of about 30-60 and a hydroxyl number of about 60-90 is esterified by adding about 5-15 weight fractions of an aliphatic alcohol comprising at least three OH-groups and about 0.1-0.5 weight fractions preferably p-toluenesulphonic acid per 100 weight fractions tall oil pitch, and by heat treatment at a lowered pressure until the acid number of the mixture is about 5-35 and the hydroxyl number is about 200-350. Aliphatic triisocyanate preferably dissolved in an inert organic solvent is added to the tall oil pitch ester thus attained in an amount such that the amount of isocyanate groups is 10-35 weight fractions per 100 weight fractions tall oil pitch ester. To the mixture thus attained is added known dilution agents and additives; the mixture is spread on a base material in a known way and the film or surface coating is finally polymerized at room temperature or at higher temperatures.