The Thermal Sensitivity Tester (TST) is a portable device designed to quantify the ability to discriminate small differences in temperature at the distal extremities of the hands and feet. The testing surfaces are two identical nickel-coated copper plates, which can be set and maintained over a wide range of temperature levels. The threshold for detecting the colder surface is determined using a two-alternative, forced-choice algorithm. The mean threshold in the normal population is 0.67 degree C and 1.01 degree C for the index finger and great toe, respectively. The TST is especially useful in diabetic neuropathy and for rapid screening of large populations under field conditions.