In a group of 50 healthy young females, pressure was determined from the right brachial artery using a direct recording technique and a standard indirect sphygmomanometer. Simultaneous recordings showed that there was a close correlation between the onset of Korotkoff sounds (phase I) and systolic pressure. Disappearance (phase V) correlated with diastolic pressure better than muffling (phase IV), but there was a very wide variation for both.