Various benzo[b]futran derivatives with a carboxymethylsulfamoyl group were prepared and evaluated for aldose reductase-inhibitory potency. Most of the compounds displayed significant inhibitory activities (IC50, 10-8-10-7M). Among the test compounds, the compounds having a carboxymethylsulfamoyl group at the 3- or 4-position exhibited the greatest inhibitory potency. Structure-activity trends of the tested compounds are discussed.