Process for preparing raloxifene hydrochloride with a purity greater than 98% and low aluminium content comprising the following stages a) demethylation of 6-methoxy-2-(4-methoxyphenyl)benzo[b]thiophene in pyridine and hydrochloric acid to obtain 6-hydroxy2-(4-hydroxyphenyl)benzo[b]thiophene in pyridine hydrochloride, b) acetylation of 6-hydroxy-2-(4hydroxyphonyl)benzo[b]thiophene with an acetylating agent to obtain the corresponding 6-acetoxy-2-(4 acetoxyphenyl)benzo[b]thiophene, c) acylation of 6-acetoxy-2-(4-acetoxyphonyl)benzo[b]thiophene with 4-(2 piperidinoethoxy)benzoylchloride hydrochloride with aluminium trichloride in halogenated solvent to obtain 6-acetoxy-2-(4acetoxyphenyl)-3-[4-(2 piperidinoethoxy)benzoyl]-benzo[b]thiophene, d) hydrolysis of 6-acetoxy-2-(4-acetoxyphenyl)-3-[4-(2-piperidinoethoxy)benzoyll benzo[b]thiophene according to the following operating conditions: d1) treatment of 6-acetoxy-2-(4-acetoxyphonyl)-3-[4-(2-piperidinoethoxy)benzoyl]benzo[b]thiophene with alkaline hydroxide in alcohol solvent, d2) acidification of the product obtained in the preceding stage (d1) with a strong acid, to obtain the corresponding raloxifene salt with the strong acid, characterised in that the strong acid used in stage (d2) is concentrated hydrochloric acid.