In a randomized controlled trial, the effectiveness of a polymeric surgical sealant (CoSeal) was compared to Gelfoam/thrombin for managing anastomotic bleeding after implantation of Dacron grafts during aortic reconstruction for nonruptured aneurysms. Each treatment was directly applied to the suture line after confirmation of anastomotic bleeding. The proportion of suture line sites that achieved immediate sealing and the proportion sealed within 5 minutes were determined among 37 experimental (59 sites) and 17 control subjects (27 sites). A significantly greater proportion of bleeding suture line sites treated with the polymeric sealant achieved immediate sealing following reestablishment of blood flow compared with control-treated sites [48 of 59 (81%) vs 10 of 27 (37%); P = 0.002]. The difference between treatment groups was maintained after 5 minutes with approximately 85 per cent (50 of 59) of CoSeal sites compared to just over one-half (14 of 27) of control sites demonstrating ultimate sealing (P = 0.01). There were no adverse events related to the use of the polymeric sealant in this study. These results support the use of this novel sealant for the intraoperative management of anastomotic bleeding during aortic reconstruction procedures.