Craniotomy and cranial reconstruction is the most common procedure for children older than 6 months with craniosynostosis. Dural sinus thrombosis after this surgery has not been well reported in the literature.This 2-year-old child underwent a bilateral craniotomy and cranial reconstruction for sagittal craniosynostosis. He had a partial thickness tear of the wall of the right transverse sinus which was uneventfully managed. Postoperative imaging showed evidence of bilateral thrombosis of the transverse sinus with a small occipital hemorrhage. He was started on low-molecular-weight heparin. Follow-up imaging showed nonprogression of the thrombosis. Four days later, he developed pulmonary hemorrhage, had an extended period of low oxygenation and hypotension with acute respiratory distress syndrome, and had to be ventilated for a prolonged period. Follow-up MRI showed evidence of extensive bilateral cortical hypointensities possibly due to hypoxemia. At the last follow-up, he continued to be grossly neurologically impaired.Thrombosis of the dural sinuses is a very rare occurrence after an extensive craniotomy and cranial reconstruction. However, it should be considered during the postoperative period and, if diagnosed, it should be treated with anticoagulants. Avoiding a direct sinus injury during reflection of the craniotomy flap and covering the exposed sinus with moist cottonoids during the surgery is advocated to prevent sinus thrombosis.