Background: The neonatal form is the most severe and most frequent type of maple syrup urine disease (MSUD). In Serbia, MSUD is not included in newborn screening programme. Objectives: Our aim is to investigate outcomes in critically ill newborns with early recognition and treatment of MSUD. Case report: Three newborns were diagnosed with MSUD in Neonatal Intensive Care Unit of our Institute during 2005-2010 period. All patients have been admitted for somnolence and poor suck beginning in the second week after birth. Diagnosis of MSUD was established within first 48 hours after admission with values of leucine ranging from 2351-2756 mcmol/L. Initial treatment included cessation of oral feeding and continuous hemodiafiltration for 24-60 hours. During the first 24 hours of treatment, we observed a 4-6 fold decrease in leucine concentration in these patients. Cognitive and physical development of all 3 patients is in normal range, with follow-up of 1-5 years. Conclusion: Early clinical recognition and urgent treatment that includes hemodiafiltration could provide normal development for children with neonatal form of MSUD. Maple syrup urine disease(MSUD)is an IEM caused by the deficiency of the branched-chain α-keto acid dehydrogenase complex,leading to the buildup of leucine, isoleucine and valine and their toxic by-products, causing acute cerebral damage and chronic sequelae.There are no epidemiological data for MSUD in Brazil, a disease not included on the national newborn screening panel. To characterize a cohort of Brazilian MSUD cases, data were collected through interview with doctors these patients. 79% of the patients were retrieved, and complete data obtained on 48 cases. Results: 72% of the cases were from Southern Brazil, 70% presented symptoms in the first 10 days of life. Metabolic formula was promptly available in 22% of the cases, and 88% presented delayed neuropsychomotor development. 52% had seizures and 62% respiratory abnormalities. There was a family history in 19% of the cases. Some of the patients who had early diagnosis did not have a normal development due to treatment failure during metabolic crisis or incorrect monitoring and biochemical control. 21% of the cases died before the age of 10 months, confirming a largely severe disease presentation.These results show that a comprehensive management program is needed in order to provide a better outcome to Brazilian MSUD patients. Objectives: There are few reports today about pregnancy in MSUD. We present two new cases with a special focus on the protocol to avoid mother metabolic decompensation (MD) at delivery. Case reports: The two patienta presented with the severe form of neonatal MSUD and experienced multiple MD from neonatal period through adulthood. The first patient is mentally handicapped and had 4 MDs during the first trimester of pregnancy. Delivery occurred at 39 weeks of pregnancy and the baby presented with intra uterine growth retardation (weight and height <10th percentile, head circumference: 25th percentile). He showed moderate developmental delay and at 12 years old, he required special schooling. Brain MRI performed at 1 year showed periventricular leucomalacia. The second pregnancy was well controlled from the beginning but the birth occurred at 32 weeks by caesarian section because of aging of the placenta. The boy also presented IUGR but has a normal development until now. The first patient experienced five MD episodes in the post-partum period, while a specific per and post-partum management protocol was performed to the second patient who did not experienced any MD. Conclusion: MSUD pregnancies must be carefully managed, mainly during the first trimester and delivery.