Thrombotic events are often diagnosed with a delay that may be responsible for definite post-thrombotic syndrome.
Case reports: We report two cases, which emphasize the difficulty of the diagnosis of venous thrombosis in two boys, at age 11 and 12 respectively. The occurrence of a leg pain led to a misdiagnosis of arthritis of hip in both cases.
Conclusion: Venous thrombosis must be searched for in children with unexplained persistent pain in leg. Precocious anticoagulation is essential for preventing post-thrombotic syndrome.