New process for industrial preparation of R-(-)-tamsulosine HCl of formula (I). In this process (R,S)-5-[2-(N-benzyl-amino)-propyl]-2-methoxy-benzenesulphonamide of formula (I), acid addition salts and enantiomers thereof and R-5-[2-[N-(2-ethoxy-phenoxy)-ethyl]-N-benzyl]-amino]-propyl-2-methoxy-benzenesulphonamide of formula (III) are new intermediates. R-(-)-tamsulosine HCl of formula (I) is prepared by reacting the secondary benzylamine of formula (II) with an alkylating agent to R-5-[2-[N-(2-ethoxy-phenoxy)-ethyl]-N-benzyl]-amino]-propyl-2-methoxy-benzenesulphonamide of formula (III), the benzyl protecting group is removed and then HCl salt is formed. The optically active compound of formula (II) is prepared by reductive condensation of (4-methoxy-3-sulphamoyl-phenyl)-acetone and benzylamine and the obtained racemic compound is optically resolved by chiral acid.