Compounds of formula (I), or a pharmaceutically acceptable salt thereof:
    Y-CO-L-Z      (I)
wherein
L      is NH or O;
Y      is a group of formula (a), (b) or (c):
wherein
R₁ and R₂, R₅ and R₆, R₉ and R₁₀,      are independently selected from hydrogen or halogen;
X      is N or CR₃ wherein
R₃      is hydrogen or C₁₋₆ alkoxy;
R₄      is hydrogen, halogen, CF₃, C₁₋₆ alkyl, C₁₋₆ alkoxy, C₁₋₆ alkylthio, C₁₋₆ alkylsulphonyl, C₁₋₆ alkylsulphinyl, C₁₋₇ acyl, cyano, C₁₋₆ alkoxycarbonyl, C₁₋₇ acylamino, hydroxy, nitro or amino, aminocarbonyl, or aminosulphonyl, optionally N-substituted by one or two groups selected from C₁₋₆ alkyl, C₃₋₈ cycloalkyl, and C₃₋₈ cycloalkyl C₁₋₄ alkyl or disubstituted by C₄ or C₅ polymethylene; phenyl or phenyl C₁₋₄ alkyl group optionally substituted in the phenyl ring by one or two of halogen, C₁₋₆ alkoxy or C₁₋₆ alkyl groups;
    one of R₇ and R₈      is C₁₋₆ alkyl and the other is C₁₋₆ alkyl, phenyl or phenyl C₁₋₄ alkyl optionally substituted in either phenyl ring by one or two of C₁₋₆ alkyl, C₁₋₆ alkoxy or halogen; or
R₇ and R₈      together are C₂₋₆ polymethylene or C₂₋₅ polymethylene interrupted by an -O- linkage;
R₁₁      is hydrogen or C₁₋₆ alkoxy;
R₁₂      is hydrogen, halogen, CF₃, C₁₋₆ alkyl, C₁₋₆ alkoxy, C₁₋₆ alkylthio, C₁₋₆ alkylsulphonyl, C₁₋₆ alkylsulphinyl, C₁₋₇ acyl, cyano, C₁₋₆ alkoxycarbonyl, C₁₋₇ acylamino, hydroxy, nitro or amino, aminocarbonyl, or aminosulphonyl, optionally N-substituted by one or two groups selected from C₁₋₆ alkyl, C₃₋₈ cycloalkyl, and C₃₋₈ cycloalkyl C₁₋₄ alkyl or disubstituted by C₄ or C₅ polymethylene; phenyl or phenyl C₁₋₄ alkyl optionally substituted in either phenyl ring by one or two of halogen, C₁₋₆ alkoxy or C₁₋₆ alkyl groups; Z      is a group of formula (d), (e) or (f):
wherein
n      is 2 or 3;
p      is 1 or 2;
q      is 1 to 3;
r      is 1 to 3; and
R₁₃ or R₁₄      is C₁₋₄ alkyl;
having 5-HT₃ receptor antagonist activity, a process for their preparation and their use as pharmaceuticals.