1-(6-Methoxy-4-quinolyl)-3-(3-vinyl-4-piperidyl)-1-propanone (viquidil, Desclidium) when administered parenterally was a potent inhibitor of thrombus formation in the microvasculature of the hamster cheek pouch. The drug was active at a minimum dose level of approximately 2.5 X 10(-4) mg/kg and