A 16-year-old hemophilia-A patient presented with symptomatic atrial septal defect (ASD). Managing bleeding during cardiovascular surgeries is a significant challenge, even for none-hemophilic patients, due to heparin administration, cardiopulmonary bypass (CPB) coagulopathy and surgical complications. This essay is an effort to discuss ASD, CPB effects on the coagulation system, and highlight some approaches to lower bleeding in hemophilic patients with congenital heart disease.