A method has been developed for MWD analysis of polyethylene oxide with M > 1 × 10 6. The MWD function was calculated on the basis of turbidimetric curves of polymer precipitation from an aqueous K 2SO 4 solution when the temperature is raised; the polymer concentration is 10 −4%. Two calculated approximations are considered and MWD data cited for some laboratory and commercial samples of high molecular polyethylene oxide.