An attempt was made to assess noninvasively the patency of aorto-coronary bypass grafts by two-dimensional echocardiography (2-D echo) in 21 patients who underwent myocardial revascularization. Fifteen patients had one graft while the other six had two grafts. All 21 patients underwent angiography 6-18 months after operation. A day before angiography a 2-D echo was performed with the aim of visualizing the bypass grafts. In 18 patients with 23 grafts (13 with 1 graft and 5 with 2 grafts) it was possible to visualize the tract of the graft by 2-D echo; 16 were judged patent on 2-D echo and confirmed by selective angiography, while 5 grafts were considered occluded both on 2-D echo and angiography. The other 2 grafts were considered to be occluded on 2-D echo but angiographic control displayed their patency. In 3 patients 2-D echo failed to visualize grafts that were patent angiographically. These data must be considered preliminary and need validation in a larger number of patients. However it is reasonable to conclude that 2-D echo has a reliable capacity to predict graft patency. Such an application may be of value in sequential control of patients with aorto-coronary bypass surgery, especially when combined with other clinical and/or technical data.