Abstract: Heteroaryloxy-.beta.-carboline derivatives of general Formula I ##STR1## wherein R.sup.1 is an optionally substituted heteroaryl residue,R.sup.2 is hydrogen, lower alkyl or lower alkoxyalkyl,X is a COOR.sup.3 -group wherein R.sup.3 means H or lower alkyl, or represents a CONR.sup.4 R.sup.5 -group wherein R.sup.4 and R.sup.5 mean respectively hydrogen or lower alkyl, R.sup.4 and R.sup.5 being capable of forming, together with the nitrogen atom, a 5- to 6-membered heterocycle, or means an oxadiazolyl residue of the formula ##STR2## wherein R.sup.6 means hydrogen, lower alkyl or cycloalkyl, are valuable pharmaceuticals.