4'-imidazolidine]-2',5'-diones were synthesized stereoselectively from (+)-, (-)-, and (+/-)-6-fluoro-3, 4-dihydro-4-oxo-2H-1-benzopyran-2-carboxylic acid [(+)-1, (-)-1, and (+/-)-1], respectively, for evaluation as new aldose reductaseinhibitors. Among these compounds, the 2S,4S compounds were found to be more potentinhibitors of aldose reductase in vitro and in vivo than the corresponding 2R,4R