A 10-month-old boy was referred for drooping and intermittent swelling in his right upper eyelid. Careful evaluation of his MRI findings along with the clinical presentation established the diagnosis of superior ophthalmic vein (SOV) thrombosis. History, old photographs, and imaging studies showed that the symptoms and signs were already present possibly since birth; however, further workup failed to reveal an underlying hematologic disorder or a congenital causative pathology. The patient was put on low-dose aspirin while waiting for the coagulation panel and genetic testing, which was stopped after 1 month of use with respect to normal test results. The symptoms except for ptosis resolved and did not recur during 6 months of follow up. To the authors' knowledge, this is the first reported case of unilateral isolated SOV thrombosis in the neonatal period.