Long carrier flights favor thromboembolism. The risk is well known to the general public but is probably really very low. The risk is however pertinent due to the volume of air travel in the world. Sitting in the same position for a long time induced venous stasis which is the principal factor favoring thrombosis in travelers, irrespective of the means of transportation. Long carrier flights also expose passengers to specific factors related to air travel: coagulation disorders and alterations of the endothelium related to hypobarism, hypoxia and low hygrometry in the cabin. Presence of pathogenic thrombophilia is not a constant factor. The prevention of venous thrombosis in air travelers calls upon simple measures: abundant hydration, avoiding use of alcohol and tobacco, walking and dorsal flexion of the feet. The only preventive option with proven efficacy is the use of elastic contention which reduces the risk of thromboembolic events. There is no consensus concerning the use of drugs proposed by certain authors; prudence should be the rule. All passengers should become aware of the risk of thromboembolism related to sitting in the same position for a long time.