Indirect measurement of the blood pressure in obese persons is still inaccurate, especially if the arm circumference deeply differs from one measure point to the other, so that the use of a wide bladder is inappropriate. Some alternative solutions have been described: oscillometric device on the arm or on the forearm, different shapes of the cuff-bladder, auscultation on the radial artery with the cuff on the forearm. We tested the capability of the Finapres device which measures the finger arterial blood pressure, beat to beat, using the volume clamp method of Penâz. In six obese patients (BMI > 30, arm circumference > 35 cm) treated for hypertension were undergoing functional respiratory tests. The finger pressure was measured simultaneously with intrabrachial on homolateral arm. Blood pressure was measured at rest and after a cold pressor test. [table: see text] The use of the Finapres seems to be possible. The correlation with the systolic is excellent, where as the correlation with the diastolic is weaker; which however is usual in any diastolic correlation between non invasive and invasive device. The CPT does not modify the correlations. Moreover the Finapres allows dynamic exploration which is of particular interest in obese persons because their blood pressure is particularly variable.