The accuracy and reproducibility of a new automatic device (P) specially designed for noninvasive blood pressure monitoring during the exercise stress test were evaluated in 50 consecutive subjects (34 normotensives and 16 hyper tensives). Automatic measurements were compared with those taken by a sphygmomanometer (RR). A good agreement between systolic pressure values obtained by the two methods was found (RR 159±30 mmHg, P 158 ± 28 mmHg, mean difference = -1.53 ± 13 mmHg, p = 0. 166, ns). On the contrary the new device significantly underestimated diastolic pressure values (RR 89.3 ± 13 mmHg; P 84±13 mmHg, mean difference -5.37±9.3, p < 0.001). In conclusion the new device seems able to measure systolic but underesti mates diastolic blood pressure both in hypertensives and in normotensives dur ing the effort test.