A case with ruptured aneurysm of the sinus of Valsalva into the right atrium directly visualized by cross-sectional echocardiography was reported. A 31-year-old male was referred to our hospital for evaluation of recently developed cardiac murmur. A systolic ejection murmur and diastolic blowing murmur were audible maximally at 3-4L and the latter one was also well audible at the right lower sternal border. Cardiac catheterization data revealed a large left-to-right shunt at the atrial level. The cross-sectional echocardiogram, obtained with a transducer at 5R towards the upwards and the medial direction, revealed a mass echo showing a pendulous motion through cardiac cycle in the right atrial cavity. Ruptured aneurysm of the sinus of Valsalva originated from the non-coronary sinus was demonstrated by aortography, and it showed the same motion as in echocardiography. From this angiographic finding and its disappearance after operation, the mass visualized by echocardiography was considered to be ruptured aneurysm itself. Thus, direct visualization of ruptured aneurysm of the sinus of Valsalva into the right atrium, as well as other types, was possible by cross-sectional echocardiography. In addition, multiple coronary A-V fistulae with a small shunt were demonstrated by coronary angiography in this case. Clinical significance of the complication has not been clarified.