Compounds of formula (I) and their pharmaceutically acceptable salts are ligands at gastrin and/or cholecystokinin receptors. X and Y are independently N—, —N(R⁵)—(R⁵ being selected from H, Me, Et, Pr, Bn, OH and —CH₂COOR⁶, wherein R⁶ represents H, Me, Et, Pr or Bn), CH—, —O— or —S—; n is from 1 to 4; A is an optionally substituted 5- or 6-membered carbocyclic ring wherein (a) 1 or 2 C atoms may optionally be replaced by N, O and/or S atoms, (b) A is fused with the aromatic group in formula (I) to form a fused bicycle, and (c) the ring containing X and Y is linked to a C atom of A; R¹ is H or C₁ to C₁₅ hydrocarbyl wherein up to three C atoms may optionally be replaced by N, O and/or S atoms and up to three H atoms may optionally be replaced by halogen atoms; R² is selected from H, Me, Et, Pr and OH, each R² being independently selected from H, Me, Et, Pr and OH when n is greater than 1; R³ (when n is 1) is selected from H, Me, Et and Pr; or (when n is greater than 1) each R³ is independently selected from H, Me, Et and Pr, or two R³ groups on neighbouring carbon atoms are linked to form a C₃ to C₆ carbocylic ring, or two R³ groups are absent from neighbouring carbon atoms which are linked by a double bond; or R² and R³ on the same carbon atom together represent an O group; R⁴ is C₁ to C₁₅ hydrocarbyl wherein up to two C atoms may optionally be replaced by N, O and/or S atoms and up to three H atoms may optionally be replaced by halogen atoms; V is —CO—NH—SO₂—Ph, —SO₂—NH—CO—PH, —CH₂OH, or a group of the formula —R⁷U, (wherein U is —COOH, tetrazolyl, —CONHOH or —SO₃H; and R⁷ is a bond; C₁ to C₆ hydrocarbylene optionally substituted by hydroxy, amino or acetamido; —O—(C₁ to C₃ alkylene)—; —SO₂NR⁸—CHR⁹—; —CO—NR⁸—CHR⁹—, R⁸ and R⁹ being independently selected from H and methyl; or —NH—(CO)_c—CH₂, c being 0 or 1); or a pharmaceutically acceptable salt thereof. Compositions comprising a compound a formula (I) are also described ##STR1##