Capsicum, a hot appetizer and seasoning, has been found to induce increased fibrinolytic activity and simultaneously cause hypocoagulability of blood when ingested or when retained in the mouth for a short time. The effect on fibrinolysis and blood coagulation of capsicum can be reproduced in the same subjects within a short time after the first stimulation. More investigations on this effect may lead to the discovery of some ideal drugs for both treatment and prevention of thromboembolism. Fibrinolytic activity measured by euglobulin lysis time in 88 Thai subjects (mean +/- SD = 167 +/- 66.84 min) was significantly higher than in 55 American whites (mean +/- SD = 254 +/- 126.70 min) residing in Thailand for a period of time (p less than 0.001). The Thai people consume capsicum with their meals. Their fibrinolytic activity, therefore, is activated several times during the day and this activation could be an important factor in causing high fibrinolytic activity. This customary habit of food ingestion is very likely a factor contributing to the racial difference in fibrinolysis. Furthermore, the Thais also have lower plasma fibrinogen and higher antithrombin III compared to Americans. These could certainly be additional factors, in addition to fibrinolytic activity, that play a role in the rarity of thromboembolism among Thais.