De-airing of the heart in open heart surgery is a necessary routine. Most of the air is evacuated from the heart before the aortic cross clamp is removed, but the de-airing may be continued even after declamping. One way to continue de-airing is to partially clamp the ascending aorta, proximally to the aortic cannula, in order to create a pocket for trapping residual air coming from the left ventricle. This paper describes a clamp specially designed and developed for this purpose. It has been used in our center since 1990 and our experience is reported. The clamp has been used on 250 patients and in 50% ultrasonography has been used to examine the heart being free from air bubbles within 20 min from releasing the aortic cross clamp. Copyright (C) 1997 Elsevier Science B.V.