Tehran University of Medical Sciences Case Reports in Clinical Practice 2538-2683 9 3 2024 12 08 114 118 EN Pedram Beigvand Gastroenterologist and Hepatologist, Babol University of Medical Sciences and Health Services, Babol, Iran. Niloofar Moradi Pediatrician, Babol University of Medical Sciences and Health Services, Babol, Iran. Sepehr Ramezani Student Research Committee,Faculty of Medicine, Babol University of Medical Sciences, Babol, Iran. Faezeh Firuzpour Student Research Committee, Babol University of Medical Sciences, Babol, Iran. AND USERN Office, Babol University of Medical Sciences, Babol, Iran. 2024 10 02 2024 10 19 Crigler-Najjar syndrome type II is a metabolic disorder stemming from mutations in the UGT1A1 gene, resulting in heightened levels of unconjugated bilirubin. Here is a case report of a 17-year-old male patient with minor thalassemia and G6PD deficiency who was referred due to worsening jaundice. He has had a history of lifelong jaundice, which has intensified over the past year and a half. Subsequently, the patient was diagnosed with Crigler-Najjar type II based on his medical history, clinical examination, and laboratory findings. Furthermore, the patient’s positive response to phenobarbital treatment confirmed the diagnosis. Consequently, it is imperative to consider CriglerNajjar syndrome in cases of unexplained unconjugated hyperbilirubinemia. https://crcp.tums.ac.ir/index.php/crcp/article/view/989 https://crcp.tums.ac.ir/index.php/crcp/article/download/989/668