A process for preparing enantiomerically pure lactams of the formula I ##STR1## where R.sup.1 and R.sup.2 are each, independently of one another, H, unsubstituted or substituted C.sub.1 -C.sub.4 -alkyl, unsubstituted or substituted C.sub.2 -C.sub.4 -alkenyl, unsubstituted or substituted aryl, (CH.sub.2).sub.n --COOH with n=0, 1, 2, 3, and X is 1, 2, 3, 4, 5, from a racemate of the formula I by. allowing a biocatalyst which selectively converts one enantiomer from I to act on the racemic mixture of I, and isolating the unconverted enantiomer from the resulting mixture of products.