Abdominal trauma is a classic but very rare cause of portal vein thrombosis. We report the case of a patient with portal vein thrombosis and cavernoma associated with portal hypertension. Anamnesis identified a serious thoraco-abdominal trauma related to a bicycle accident 6 months before. Biological screening identified an inherited heterozygous G20210A factor II gene mutation which supports a recent notion that portal vein thrombosis most often occurs when both local and systemic aetiological factors are combined.