Citrin deficiency resulting from mutations of the SLC25A13 gene is associated with two major clinical phenotypes; neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD) and adult-onset type 2 citrullinemia (CTLN2). In Korea, 6 cases of citrin deficiency were diagnosed based on biochemical and molecular findings. Four NICCD patients (2 boys and 2 girls) presented high citrulline levels on a newborn screening test or neonatal cholestasis. They were associated with conjugated hyperbilirubinemia, elevated liver enzymes, hypoalbuminemia, mild hyperammonemia, elevated citrulline, methionine and threonine. All of the hepatic manifestations were resolved spontaneously at the age of 5-9 months. Mutation analysis identified them as compound heterozygotes carrying each of the c.851del4, IVS11+1G>A, IVS13+1G>A, G393S, and IVS16ins3kb mutant alleles. Two adult male CTLN2 patients were identified. They were aged 24 and 37 years, and presented sudden loss of consciousness, hyperammonemia and citrullinemia. They were compound heterozygotes with IVS13+1G>A and IVS16ins3kb, and with c.851del4 and IVS11+1G>A mutant alleles. This report describes the clinical characteristics, biochemical findings and molecular analysis of the SLC25A13 gene of patients with citrin deficiency in Korea.