Thiazolidine-2, 4-dione derivatives having one or two substituent (s) such as phenyl, heteryl and alkyl group (s) at the 5-position were synthesized and evaluated as aldose reductase inhibitors. Inhibition by the active compounds of the swelling of the lens in a rat-lens-culture assay was also measured. Among these compounds, a series of 5-(3, 4-dialkoxyphenyl) thiazolidine-2, 4-diones showed pronounced activities in both assays. Structure-activity relationships are discussed and a new approach to the synthesis of 5-arylthiazolidine-2, 4-diones is described.