It was demonstrated that potent and selective ligands for the 5-HT4 receptor devoid of 5-HT3 receptor antagonist properties could be designed from the esters of 4-amino-5-chloro-2-methoxybenzoic acid and the conformationally flexible piperidine framework derived from the locked structure of the quinuclidine ring of zacopride. The compounds were evaluated in binding assays with (^3H)^2-GR-113808 and (^3H)^2-BRL-43694 and fonctionally using electrically-evoked contractions in the guinea-pig ileum. Compound 7 exhibited nanomolar 5-HT4 receptor agonist activity.