NOVELTY - Crude heparin sodium dissolved in purified water is reacted with benzethonium chloride to obtain heparin benzethonium chloride salt. The chloride salt dissolved in N,N-dimethylformamide is reacted with benzyl chloride, and ethanol solution of saturated sodium acetate trihydrate to obtain heparin benzyl ester. The ester is dissolved in purified water, reacted with solid sodium hydroxide, and filtered. Ethanol is added to the filtrate and the mixture is cooled to obtain a precipitate. The precipitate is collected and purified to obtain enoxaparin sodium.    USE - Manufacture of enoxaparin sodium.    ADVANTAGE - The enoxaparin sodium is manufactured with reduced usage of organic solvent, with improved productivity, by a simple process.    DETAILED DESCRIPTION - Crude heparin sodium is dissolved in purified water to obtain 10-15 wt.% crude heparin sodium solution. The pH of the solution is adjusted to 5.0-7.0 using hydrochloric acid or sodium hydroxide. Ethanol is added to the solution and precipitate is collected. Purified water is added to the precipitate and dissolved completely. Hydrogen peroxide is added to the mixture to oxidize, and the mixture is filtered with a film. Ethanol is added to the mixture and further precipitated to obtain a precipitate (b). Water is added to the precipitate (b) to dissolve heparin sodium solution. Benzethonium chloride is added and agitated. The mixture is centrifuged and the precipitate is collected, washed with water and dried at 60-70 degrees C to obtain heparin benzethonium chloride salt. The obtained salt is dissolved in N,N-dimethylformamide solution. Benzyl chloride is added to the solution and reacted for 10-15 hours at 25-30 degrees C. Ethanol solution of saturated sodium acetate trihydrate is added to the reaction mixture and stirred. The stirring is stopped and the precipitate obtained is collected to obtain heparin benzyl ester. The obtained ester is dissolved in purified water, and 10-15 wt.% solid sodium hydroxide is added and reacted for 15-70 minutes at 60-65 degrees C. Hydrochloric acid (2 mol/L) is added to adjust the pH to 6.0-8.0, and the mixture is filtered with a film. Ethanol is added to the filtrate and the mixture is cooled to 0-10 degrees C to obtain a precipitate. The precipitate is collected to obtain crude enoxaparin sodium. Purified water is added to the crude product and dissolved completely. A resin is added to adsorb sulfate, and agitated at 30-50 degrees C. The mixture is filtered with a film and oxidized with hydrogen peroxide to precipitate. The precipitate obtained is dissolved in water and filtered, and spray dried to obtain enoxaparin sodium.