A series of N-acyl amino acid analogues of 2 (1H)-quinolinone was synthesized and tested for antiulcer activity against acetic acid-induced gastric ulcer in rats. These compounds were synthesized by the acylation of amino acid derivatives of 2 (1H)-quinolinone, which were obtained from the reaction of ω-bromoalkyl 2 (1H)-quinolinones and acetamidomalonate in the presence of sodium ethoxide, followed by hydrolysis with diluted hydrochloric acid. Among them, 2-(4-chlorobenzoylamino)-3-[2 (1H)-quinolinon-4-yl] propionic acid (VIIIf) was found to have the most potent activity. The structure-activity relationships are discussed.