Travel-related thrombosis occurs in 1/6,000 individuals who fly long-haul flights. The risk is increased significantly in passengers with thrombophilia and during hormonal therapy. Pregnancy is a hypercoagulable state with 5-10-fold increase in VTE risk. Mechanisms for hypercoagulation on air are related to cabin atmospheric conditions, with immobility and flight duration playing a major role. Prophylactic measures include frequent exercise in all passengers, elastic stockings and LMWH in travelers at high risk.