New piperidinyl- or piperazinyl-substituted-1,2,3,4-tetrahydronaphthalene derivatives having the formula ##STR1## wherein X is N or CH; Y is NR.sub.2 CH.sub.2, CH.sub.2 --NR.sub.2, NR.sub.2 --CO, CO--NR.sub.2 or NR.sub.2 SO.sub.2 ; R.sub.1 is H, C.sub.1 -C.sub.6 alkyl or C.sub.3 -C.sub.6 cycloalkyl; R.sub.3 is C.sub.1 -C.sub.6 alkyl, C.sub.3 -C.sub.6 cycloalkyl or (CH.sub.2).sub.n -aryl, where aryl is phenyl or a heteroaromatic ring containing one or two heteroatoms selected from N, O and S and which may be mono- or di-substituted; n is 0-4; as (R)-enantiomer, (S)-enantiomer or a racemate in the form of the free base or a pharmaceutically acceptable salt or hydrate thereof; a pharmaceutical formulation containing the compounds, use of the compounds in the treatment of 5-hydroxytryptamine mediated disorders, processes for the preparation of the compounds and intermediates for the preparation of the compounds.