Posterior reversible encephalopathy syndrome (PRES) is a radioclinical entity associating a reversible central nervous system involvement with a common brain imaging feature. There is a great variability in the clinical presentation of this syndrome and in the features of its sometimes atypical imaging appearance. PRES is an unusual neurological complication occurring during pregnancy or in the post-partum period, other than any pre-existing pathology occurred during pregnancy. Vasogenic edema due to the rupture of the blood-brain barrier seems to be its main cause. We here report the case of a primiparous patient with generalized tonic-clonic seizures associated with hypertensive peak occurred during the third trimester of pregnancy. Magnetic resonance imaging (MRI) of the brain showed posterior reversible encephalopathy. PRES should be suspected in patients with any sign of neurological disorder. It has a favorable outcome without sequelae under early and fast treatment.