Quantitative determinations were made of vibration perception thresholds (VPTs) at six different measurement sites in 202 healthy subjects of working age (16-68 years). Measurements were made with a commercially available device, the frequency of vibrations being 100 Hz. The temperature of the skin at the measurement sites was also determined. The effect of temperature on VPT values was evaluated separately in eight test subjects. In addition, determinations were made of intraindividual variations in VPT values and it was found that there was an almost 100% variation under identical conditions. Variation in VPTs caused by temperature was only slightly greater than intraindividual variation from day to day. It did not seem to be necessary, for the making of measurements, to take into account variations of temperature within physiological limits. VPT was found to increase exponentially with age, more steeply among men than women. In practice, it is most important when making VPT measurements to take into account the age and sex of the subject and possibly also to allow for thresholds slightly higher than usual with subjects engaged in physical work. An important field of application for this method is in occupational health services, where there is a need for a simple and reliable screening test when attempting to diagnose polyneuropathy. The method is also very suitable for determining the neurotoxic effect of different drugs.