Traumatic isolated oculomotor nerve palsy with negative imaging studies is extremely rare. We reported such a case who after head injury had normal brain computerized tomography (CT), magnetic resonance imaging (MRI), and angiography. The absence of other neurological signs and normal brain MRI indicated the lesion was most likely within the subarachnoid space, as the other important structures near the third nerve, such as the brainstem, cavernous sinus and orbit, were undamaged. The prognosis of traumatic oculomotor palsy is usually poor. Generally speaking, patients experience more rapid and complete recovery of ptosis than of extraocular movements, while pupillary size and light reflex show the least degree of recovery. Further case collections with modern imaging studies are needed to clarify the mechanisms and clinical characteristics associated with this phenomenon.