An improved synthesis of N-phenylanthranilic acid using water as solvent can be achieved by ultrasound irradiation. A number of N-phenylanthranilic acids were prepared in good yields in a very short reaction time. ... An improved synthesis of N-phenylanthranilic acid using water as solvent can be achieved by ultrasound irradiation. A number of N-phenylanthranilic acids were prepared in good yields in a very short reaction time.