Using an improved biothesiometer, intraindividual variability of vibratory perception thresholds was investigated in 60 healthy volunteers, 39 diabetics with diabetic neuropathy and 21 diabetics without symptoms or signs of neuropathy. Reproducibility of vibratory perception thresholds was satisfactory in the normal subjects and most diabetic patients. However, a considerable variability was found in some diabetics. For determination of vibratory thresholds, vibrometers with amplitude measurement and controlled application pressure are recommended. In longitudinal studies of patients with diabetic neuropathy, a combination of neurophysiological test methods should be used to monitor impaired nerve function.