Isolated lateral sinus thrombosis (LST) was mentioned in the past as a complication of middle ear infection. In the recent years, it was not frequently studied. Our patient, a 23-year-old woman who was taking an oral contraceptive pill, displayed 24 hours of migraine, such as headache; her systemic examinations were normal. She underwent neuroimaging examinations in the first 36 hours of admission. Native head computed tomography (CT) revealed hyperdensities along the left tentorium, involving the left lateral sinus (LS). Cranial magnetic resonance imaging (MRI) showed hypointense signal on MRI T2*SW (susceptibility-weighted) in the region of the left LS. MR venography noted the absence of flow-related signal within the left LS. The clinical symptoms, signs and neuroimaging results formulated the diagnosis of left isolated LS thrombosis. Laboratory data demonstrated an elevated D-dimer and homozygosity for the factor V Leiden mutation. She was immediately started on anticoagulation in the form of low-molecular-weight Heparin; then, she was treated with Warfarin for an indefinite duration. The headaches resolved within two days and her neurological examination was also normal. A second MR venography achieved after two weeks demonstrated complete recanalization of the venous sinuses. We did not observe any LST recurrence, deep vein thrombosis or pulmonary embolism during one year of follow-up. The early initialization of anticoagulation produced a favorable evolution. An acute isolated left LST could be identified in her case on the head CT combined with MRI and MR venography.