NEW MATERIAL:An oxazole derivative shown by the formula I (R1 is phenyl which may be replaced with Cl; R2 is N-methylcarbamoyl, ethoxyamido, p- chlorobenzyloxyamido, ω-methylureido, or ω-phenylureido).

EXAMPLE: 5-Phenyl-2-oxazolecarbomethylamide.

USE: An inhibitor against aldose reductase. A preventive or remedy for diabetic complication. Effective against diabetic cataract, diabetic neuropathy, diabetic retinopathy, etc. Having extremely low toxicity.

PREPARATION: For example, a compound shown by the formula I wherein R1 is phenyl and R2 is methylcarbamoyl is obtained by reacting a compound shown by the formula II with methylamine. The compound shown by the formula II, for example, is prepared by reacting benzoylmethylamine hydrochloride with ethyl chloroglyoxylate to give ethyl N-benzoylmethylaminoglyoxylate, which is subjected to ring closure with phosphorus oxychloride.