Intraoperative dye curves are routinely employed following closure of all types of intracardiac defects. The technique has been quite helpful in a variety of problems. With atrial defects which are low in the septum or when arterial desaturation occurs immediately postoperatively, it is important that inferior vena caval, as well as superior vena caval injection of dye be obtained. In the past two years, intraoperative dye curves have been employed in approximately 75 patients following ASD repair without evidence of iatrogenic diversion of blood flow from the inferior vena cava to the left atrium in any patient. It is a simple technique which can detect this error at the time of surgery and thus permit its immediate correction and can be strongly recommended as a routine procedure.