Measurement of arterial preseure, either intermittently or continuously has teen used for almost 100 clears. A prospective study was conducted on 22 patients to compare the accuracy of arterial pressures treasured br a non-invasive (ACCUTORR,ACC) and an invasive (intra-arterial Line, IAL) arterial pressure monitoring systems. Overall, the accuracy or regroducibility of each method, as expressed in the individual variarlce, was shown to be statistically in significant between ACC and IA7. The difference in arterial pressures was particularly marked between ACC and IAL when srstalic BP was either less than 100 mmHg or greater than 140 mmHg.