Tetrahydrocarbazole derivatives of the general formula I ##STR1## in which Thc is a 1,2,3,4-tetrahydro-3-carbazolyl radical which can be substituted once or twice by alkyl, O-alkyl, S-alkyl, SO-alkyl, SO.sub.2 -alkyl, OH, F, Cl, Br, CF.sub.3 and/or CN or by a methylenedioxy group, the two radicals Y are each H or together are a C--C bond, one radical Z is Ar and the other radical Z is H, A is --CH.sub.2 -- or --CH.sub.2 CH.sub.2 -- and Ar is a phenyl group which is unsubstituted or substituted once or twice by alkyl, O-alkyl, S-alkyl, SO-alkyl, SO.sub.2 -alkyl, OH, F, Cl, Br, CF.sub.3 and/or CN or by a methylenedioxy group, or is a 2- or 3-thienyl radical, and in which the alkyl groups each have 1-4 C atoms, and their physiologically acceptable acid addition salts have effects on the central nervous system.