Guidelines on arterial blood pressure (BP) measurements recommend a time interval between readings. There has been little evidence supporting this recommendation. Therefore, we measured the variation in arterial pressure between the pairs of measurements without an interval (n = 269) or with venous congestion interposed (n = 79). The variation in BP readings was not significantly greater whether a 60-sec interval or venous congestion were present. These overall results do not support the hypothesis that the absence of the time interval or of presence of venous congestion, as may occur in clinical practice, significantly affects BP measurements.