Abstract The shape of the venous tracing in various heart diseases is discussed. In tricuspid stenosis the a waves are always tall. This is usually also the case in pulmonic stenosis and in high pulmonary arterial pressure. However, in these conditions the a waves may be low if they happen to occur in early diastole. This is due to the low resistance to ventricular filling during that phase of the cycle. For an appreciation of the height of the a wave it is important, therefore, to take the heart rate into account. With atrial fibrillation the a wave is absent, and the x depression is only present after the c wave, whereas the y depression is deeper than the x depression. With sinus rhythm and tricuspid insufficiency the x depression is present in a normal way after the a wave, but it is flattened after the c wave and may disappear if the tricuspid insufficiency is severe enough. In atrial fibrillation associated with tricuspid insufficiency the x depression may fail to appear. In tricuspid insufficiency there is a deep y depression and a distinct early h wave, whereas in tricuspid stenosis the y depression is shallow and the h wave is late or absent. In atrial septal defect the shape of the venous tracing is usually within normal limits, but shows constantly abnormal features after operation. The a wave is small or absent, and the y depression is deeper than the x depression. Possible responsible factors are considered to be the smaller volume of blood entering the dilated right ventricle and the damage inflicted on the right atrium by surgery. Similar postoperative features are seen in ventricular septal defect. The venous tracing is useful as a reference tracing for the phonocardiogram. It reflects accurately the changes in right atrial pressure, without appreciable delay. Every venous tracing with the x depression ending after the second heart sound should be considered suspect as being disturbed by arterial pulsations, and is not reliable as a reference tracing for the phonocardiogram, insofar as the summit of the v wave is concerned. The right atrial sound is synchronous with the jugular a wave. The opening snap from the right heart is synchronous with the summit of the v wave; the opening snap from the left heart often occurs before the summit. The third heart sound from the right heart is synchronous with the y depression, whereas the third heart sound from the left heart may be synchronous with the y depression or occurs during the descending limb of the v wave. In pulmonary hypertension the distance between the pulmonary component of the second sound and the summit of the v wave is greater than in cases in which pulmonary pressure is normal or lower than normal. The mid-diastolic murmurs due to functional tricuspid and mitral insufficiency do not pass the y depression; the same applies to the protodiastolic murmur of pulmonary insufficiency in patients with normal or low pulmonary pressure. In contrast, every mid-diastolic murmur that continues distinctly beyond the y depression is due to an organic lesion of the tricuspid or mitral orifice.