Laser-Doppler flowmetry (LDF) is a non-invasive technique for measuring the tissue blood flow. It has been shown in the skin that LDF discloses blood flow fluctuations due to vasomotor nerve activity. LDF can give measurements of blood flow at various sites of different tissue. Furthermore, LDF may enable selective measurement of blood flow at different depths within the tissue, when the device and the probe are appropriately chosen. Thus, LDF is available for examining vasomotor responses at various tissue sites. For clinical application, a method for calibrating the LDF signal in absolute units should be established.