Method for producing nalmefene hydrochloride from naltrexone, which method is particular well adapted for large-scale industrial application, and has been found to be efficient, to give a high yield and to afford highly pure nalmefene hydrochloride salt.本發明係關於一種由納曲酮(naltrexone)製造納美芬鹽酸鹽(nalmefene hydrochloride)之方法,該方法尤其適合於大規模工業應用,且已被發現有效、產率高且提供高純度納美芬鹽酸鹽。