Varicella is a benign infectious disease that is rarely complicated by thrombosis. Factor V Leiden (FVL) mutation is presently recognized as the most common inherited cause of thrombosis. From a case report the link between varicella associated thrombosis and FVL is discussed.An eight year-old boy was admitted on 15th day of a varicella infection for difficulty to walk and painful legs. Doppler ultra sound of the lower limbs venous system showed thrombosis of the left iliac vein and femoral veins. Thrombophilia work-up revealed a FVL heterozygotic status for the patient. Biological screening for molecular abnormalities associated with thrombophilia led to the detection of a heterozygous inherited FVL mutation in the patient. Response to heparine followed by oral anticoagulant treatment was good.Thrombosis associated with varicella in child is a rare event. We recommend to realize a thrombophilia screening in such patients. We also support varicella vaccination of children identified as having constitutional prothrombotic disorders like FVL mutation.