Abstract: A 3-substituted 3,4,5,6,7,8-hexahydropyrido[4′,3′:4,5]thieno[2,3-d]pyrimidine compound of formula I wherein R1 is hydrogen, C1-C4-alkyl, acetyl or benzoyl, optionally substituted phenyl-C1-C4-alkyl, naphthyl-C1-C3-alkyl, phenyl-C2-C3-alkanone or a phenylcarbamoyl-C2-alkyl, R2 is optionally substituted phenyl, pyridyl, pyrimidyl or pyrazinyl, or an optionally substituted bicyclus wherein one of the two fused rings is a phenyl, a pyridyl, a pyrimidyl or a pyrazinyl ring, A is NH or oxygen, B is hydrogen or methyl, C is hydrogen, methyl or hydroxyl, X is nitrogen, Y is CH2, CH2—C2, CH2—C2—CH2 or CH2—CH, Z is nitrogen, C or CH, and the linkage between Y and Z is a single or a double bond, and n is 2, 3 or 4, or a physiologically tolerated salt thereof, and compositions comprising them and their use as antagonists of 5HT1B and 5HT1A and for the treatment of depression and related disorders.