Tehran University of Medical Sciences Case Reports in Clinical Practice 2538-2683 5 4 2021 01 16 106 109 Pantea Tajik Dapartment of pediatricsSemnan University of Medical Sciences, Semnan, Iran. Amir Hossein Goudarzian Student Research Committee, Mazandaran University of Medical Sciences, Sari, Iran. Zeinab Pourzahabi Department of Pediatrics, Amiralmomenin Hospital, Semnan University of Medical Sciences, Semnan, IranDepartment of Pediatrics, Amiralmomenin Hospital, Semnan University of Medical Sciences, Semnan, Iran. 2020 03 26 2020 05 05 Background: Carnitine palmitoyltransferase-1 (CPT-1) deficiency is a rare autosomal recessive disorder of mitochondrial long-chain fatty acid oxidation with fewer than 30 case reports.  Case report: A 30-month-old child with fever and loss of consciousness was referred to our hospital. She had symptoms of colds for three days that were treated, but she had anorexia. Her abdomen was soft and hepatomegaly 5 cm below the edge of the rib was detected. According to a neurological consultation, with the probability of a seizure, the patient began to receive levetiracetam. The patient was treated with sodium benzoate due to her decreased level of consciousness and increased blood ammonia (300). In the acylcarnitine profile, mildly elevated levels of single acylcarnitine were seen to confirm the diagnosis of CPT-1 deficiency. Conclusions: CPT-1 deficiency is a rare autosomal recessive defect of mitochondrial long- chain fatty acid oxidation that presents as an acute “Reye-like” hepatic encephalopathy and non-ketotic hypoglycemia, developmental delay, and hepatomegaly. https://crcp.tums.ac.ir/index.php/crcp/article/view/344 https://crcp.tums.ac.ir/index.php/crcp/article/download/344/369