A series of 2-anilino-1,6-dihydro-6-oxo-5-pyrimidinecarboxylic acids with various substituents was synthesized and evaluated in the rat passive cutaneous anaphylaxis test for antiallergic activity. High activity by intraperitoneal and oral administrations was observed for the 3-trifluoromethyl and 2-alkoxyanilino derivatives (64, 79, 81, 82 and 85). Structure-activity relationships are discussed.