Objective of this study was to identify mutations in the ABCC8 and KCNJ11, HNF4A and GLUD genes, genotype and phenotype correlations of children with congenital hyperinsulinism. A prospective study was conducted on 32 cases with congenital hyperinsulinism diagnosed and treated at the National Hospital of Pediatric from January 2010 to September 2012. The criteria used for diagnosis was designed by Hussain K 2008. The results showed that 43.8 percent were detected with genes mutation, including ABCC8 (37,6 percent), KCNJ11 (3.1 percent), HNF4A (3.1 percent).100 percent cases who has two recessive mutations or one dominant gene mutation from the father of ABCC8, do not respond to diazoxide treatment and must undergo near total (95 percent) pancreatectomy, with other cases who do not have mutation usually respond to diazoxide. In conclusion, for children with congenital hyperinsulinism, it's necessary to take genetic testing to detect gene mutations in order to make an appropriate decision for medical treatment. Family with a child diagnosed with congenital hyperinsulinism need genetic counseling, prenatal diagnosis and follow up treatment immediately after delivery.