We present the case report of a child with Factor V Leiden mutation who underwent Fontan procedure. Thromboembolism is a widely recognized complication of the Fontan procedure and its modifications. Factor V Leiden mutation, being a hypercoagulable state, posed a higher risk for thromboembolism in this child. Appropriate measures taken before and after surgery prevented postoperative coagulopathy.
Keywords: Factor V Leiden mutation; Fontan; thromboembolism.