Acute intermittent porphyria (AIP) is an autosomal dominant metabolic disorder due to hydroxymethylbilane synthase deficiency in heme biosynthesis. Acute attacks manifest as a combination of an acute onset abdominal pain, autonomic dysfunction, acute motor neuropathy and rarely acute encephalopathy. The combination of symptoms is unique for each patient. Acute encephalopathy with mental symptoms, unconsciousness or delirium, hallucinations, epileptic seizures, headache and more seldom focal neurological deficiency may be a prominent feature of acute porphyric attack in some cases. The diagnosis of AIP is biochemical and based on more than 5-fold increase of urine porphobilinogen during an acute attack. The pathogenesis of acute porphyric encephalopathy was unclear until recently since the autopsy material of AIP patients deceased due to an acute attack did not reveal any specific lesions. In addition, porphyrin precursor, aminolevulinic acid (ALA), the main recognized neurotoxin for acute autonomic and peripheral neuropathy in AIP, has very low permeability for blood-brain barrier. The single case reports of MRI findings in AIP patients comparable with posterior reversible encephalopathy syndrome (PRES) may elucidate pathogenesis of acute porphyric encephalopathy since PRES univocally indicates disturbed permeability of blood-brain barrier and following brain edema. Novel MRI techniques, such as DWI, ADC mapping exclude ischemia. In a current paper, we report our case of PRES during an acute porphyric attack manifested with encephalopathy and the relevant literature review of all similar published cases.