A novel series of furan-2-one and pyrrolin-2-one derivatives having PAI-1 (plasminogen activator inhibitor-1) inhibitory activity were synthesized and evaluated for their antithrombotic activity in a rat arterial thrombosis model. Among the synthesized compounds, 5f (T-1776Na) was found to have good selectivity for PAI-1 over other enzymes and high antithrombotic activity.