Objective: A retrospective study was undertaken to evaluate early and mid-term results in infants with congenital heart defects, weighing less than 2500g, who underwent cardiac surgery other than patent ductus arteriosus closure. Methods: From January 2000 to December 2008, 79 patients underwent surgical treatment of congenital heart malformations at our institution. Surgery included a complete correction in 38 patients and a palliative procedure in 41. Mean age at operation was 29,4 days (7 day–160 days). Mean weight was 2265g (1200g-2500g). 70 children were born prematurely. 40,5% of neonates were ventilated preoperatively. Heart defects included mainly: coarctation of the aorta (17), transposition of the great arteries (15), hypoplastic left heart syndrome (12), tetralogy of Fallot (8), ventricular septal defect (5), double-outlet right ventricle (5), pulmonary atresia (5), truncus artriosus (4). 30 neonates underwent cardiac surgery requiring extracorporeal circulation. Deep hypothermia with circulatory arrest was used in 13. Results: Early surgical mortality was 21,5%: 7 neonates died after definitive repair (18,6%) and 10 after palliation (24,4%). Overall (early and late) survival was 67,1% (76,3% after correction and 58,5% after palliation). Postoperative morbidity occurred in 42 patients (53%), mainly: pneumonia, low cardiac output, bleeding. Neurological complications occurred in 7 patients. 9 neonates required surgical or invasive cardiological interventions. Clinical state of the patient, type of the operation and use of deep hypothermia with circulatory arrest influenced higher mortality and morbidity. Conclusions: Surgery for congenital heart disease can be performed in low weight critically ill infants with reduced, but acceptable early and mid-term survival.