Background and aims: Performing ballon atrial septostomy (BAS) is invaluable in patients with ductal dependent congenital heart defect (CHD). Defect in the atrial septum is created using ultrasound controlled ballon catheter. Aims: The aim this study is to show efficacy of ultrasound controlled BAS. Methods: This retrospective - prospective study was performed from January 2003 to December 2013, included 20 congenital heart defects, with indication for ultrasound controlled BAS. Patients were sort by oxigen saturation before and after BAS as well as measurements of created defect in the interatrial septum. Results: Transposition of the great arteries occured in 75%, pulmonary atresia in the 15%, tricuspidal atresia in the 10% patients.The male sex predominated (65%), median age was 5 days (1 - 20 days) and the median weight was 3200 +/- 450 grams. Access via femoral vein was in 85% patients while umbilical vein access was in 15% of patients. Oxigen arterial saturation, which is an indicator of success of procedure, was higher than 60% in 16 patients after 5 minutes, while two patients underwent surgical corection.The size of the defect after BAS was 3–5 mm greater than start mesurement in 75% patients (p<0,005). Conclusions: Ultrasound controlled BAS offers fast and efficient team treatment, performed in PICU, at bedside, reducing harmful effects of X radiation.We recommend Colour two-dimensional ultrasound techique for fast diagnosis and treatment.