The paper describes a three-wave remote laser method of measuring the oil film thickness at the rough sea surface based on the determination of the oil film transmission coefficient. Mathematical modeling shows that the method makes it possible to measure the oil film thickness between 5 and 140 μm. The mean error of the determination, in most cases, is no less than 15% in a series of 30 measurements at a relative root-mean-square value of measurement noise of 2%.