Calibrated jugular pulse tracings and cardiac catheterisation were performed on 50 consecutive patients with organic heart disease. Twenty normal adults had calibrated jugular pulse tracings and served as controls. The height of the jugular 'A' and 'V' waves was quantified as a percentage of a known displacement, rendering measurements independent of the amplification used in recording technique. A close correlation existed between the size of the calibrated jugular 'A' and 'V' waves and the actual magnitude of the right intra-atrial pressure changes (A wave, r = 0.72; V wave, r = 0.80). Patients who were free of pulmonary hypertension or tricuspid disease had calibrated 'A' and 'V' waves similar in height to the control population. An enlarged 'A' wave was usually associated with conditions restricting flow into the right ventricle. An enlarged 'V' wave generally indicated tricuspid regurgitation. These changes are often subtle and are not apparent in conventional venous tracings or at the bedside. We conclude that the calibrated jugular pulse tracings can accurately separate normal from abnormal venous waves and expand the diagnostic potential of the jugular pulse.