We sought to evaluate the utility and safety of CoSeal Surgical Sealant (Baxter) for the prevention of cardiac adhesions in children. Seven cardiac surgery centers in Europe recruited consecutive pediatric patients requiring primary sternotomy for staged repair of congenital heart defects. Exclusion criteria included immune system disorder, unplanned reoperation, or reoperation within three months of primary repair. CoSeal was sprayed onto the surface of the heart at the end of surgery. Evaluation of adhesions took place at first reoperation. Data on safety, duration of surgery, and ease of CoSeal use were also collected. Seventy-nine pediatric patients were recruited between February 2005 and September 2007. Of these, 76 underwent major surgery to repair a wide range of congenital heart defects. Thirty-six patients underwent reoperation >3 months after primary repair, and were included in the efficacy analysis. Mean adhesions score was 8.3 (standard deviation [S.D.] 2.4; range 7-16). Six adverse events (5 serious) were possibly/definitely attributed to CoSeal. CoSeal's ease of use at primary operation was graded by surgeons as 12.1 mm (S.D. 9.8) on a visual analog scale of 0 ('very easy') to 100 mm ('very difficult'). Results of this prospective uncontrolled trial justify further investigation in a randomized, controlled trial