Novel oxazolidinones of the formula I ##STR1## Z is O or S, R.sup.1 and R.sup.2 are each phenyl or benzyl radicals which are unsubstituted or mono- or disubstituted by alkyl, alkoxy, alkylthio, alkylsulfinyl and/or alkylsulfonyl having each 1-4 C atoms, alkanoyloxy and/or alkanoylamino having each 1-6 C atoms, F, Cl, Br, OH and/or CF.sub.3 or are heteroaryl radicals containing 1-4 heteroatoms and R.sup.3 and R.sup.4 are each H, alkyl or alkoxy having each 1-4 C atoms or are F, Cl, Br, OH or CF.sub.3, and also their salts have effects on the central nervous system, in particular neuroleptic effects.