Abstract The events of the cardiac cycle are re-evaluated on the basis of newer ideas of inertial states, compliance, and similar hemodynamic principles by the use of more precise, modern recording equipment. While these events generally agree with classic schemes, certain discrepancies which tend to cause inaccurate measurement are presented. In particular, the intervals existing between A-V valve closure and the onset of the first sound, and between semilunar valve closure and the onset of the second sound are discussed. Causes of prolongation of the intervals between valve closures and sound events are briefly discussed. The possibility of inaccurate measurements by noninvasive techniques is further considered.