Abstract: The invention disclosed relates to the biological production of substantially isomerically pure (R)-baclofen and structurally related compounds, from the racemic mixture of (R)- and (S)-isomers thereof, and to the isolation of a Streptomyces microorganism from Nature which is capable of preferentially metabolizing one of the isomers while showing minimal metabolic activity on the other isomer. A fermentation or bioconversion process using this microorganism or the cell-free enzymes derived therefrom for the biological resolution of a racemic mixture of (R)- and (S)-baclofen and structurally related compounds is also disclosed.