Abstract: This invention relates to a process for the separation of moprolol into its two optical antipodes, substantially characterized by the fact of salifying racemic moprolol with L(+)glutamic acid; treating the thus obtained mixture of diastereoisomeric salts with a water/alcohol mixture, in this way separating the L(+)glutamate insoluble salt of (+)moprolol; treating the resultant mother liquors which contain in solution the L(+)glutamate salt of (-)moprolol with a base so as to separate the laevorotatory isomer of crystalline moprolol, which finally undergoes a purification. The invention also relates to a pharmaceutical composition containing said laevorotatoryisomer of moprolol.