A combination of 2-acetoxy-5-(.alpha.-cyclopropylcarbonyl-2-fluorobenzyl)-4,5,6,7-tetrahyd- rothieno[3,2-c]pyridine or a pharmaceutically acceptable salt thereof, and aspirin, which possess excellent inhibitory activity against platelet aggregation and thrombogenesis, and is useful for preventing or treating diseases caused by thrombus or embolus.