Abstract: Novel 3-aryl-3-cycloalkyl-piperidine-2,6-dione derivatives of the general formula I: ##STR1## in which A is a 4-aminophenyl radical or a pyridyl-(4)-radical and R.sub.1 is a saturated or unsaturated C.sub.3 -C.sub.10 -cycloalkyl radical or a C.sub.3 -C.sub.12 -alkenyl radical as well as physiologically acceptable salts thereof. The compounds are useful as inhibitors of estrogen biosynthesis. The compounds are made by a process which includes the step of heating a compound of the formula II ##STR2## wherein A and R.sub.1 have the meanings given above, and in addition A may also be a phenyl radical or a 4-nitrophenyl radical, X and Y are the same or different and repesent CN or COOC.sub.1 -C.sub.6 -alkyl and X or Y may also be COOH or a carboxylic acid ester group of the formula COOC.sub.1 -C.sub.6 -alkyl group, in a high boiling solvent at a temperature between 50.degree. and 200.degree. C. in particular between 80.degree. and 100.degree. C.