Several 5-benzyl-2, 4-thiazolidinediones (5–7) were synthesised and tested as in vitro aldose reductase (ALR2) inhibitors. Most of them, particularly N-unsubstituted 5-benzyl-2, 4- thiazolidinediones 5 and (5-benzyl-2, 4-dioxothiazolidin-3-yl) acetic acids 7, displayed moderate to high inhibitory activity levels. In detail, the insertion of an acetic chain on N-3 significantly enhanced ALR2 inhibitory potency, leading to acids 7 which proved to be the ...