Measurement of vibratory perception threshold was carried out on the internal malleoli of 73 healthy subjects and 26 diabetic patients with symptoms of polyneuropathy in their legs. The tests were done first with a tuning fork, using a measuring scale to reflect the amplitude of vibration, and then with an electromagnetic vibrameter (Somedic AB, Stockholm). The results obtained using the vibrameter were much more sensitive than those recorded with the tuning fork (12 and 3 pathological results respectively, in 26 patients). Vibratory perception sensitively reflects disturbances of the function of fast adapting mechanoreceptors and of thick myelinated sensory nerve fibres. The results proved to be readily reproducible. Some variability was noted in the normal values obtained: A further development of the method to exclude the influence of reaction times of patient and investigator on the results might reduce this variability.