The purpose of this study was to investigate the relation between nerve conduction velocity (NCV) and some factors which affect the measurement, such as age, skin temperature, body build and alcohol consumption. Neurophysiological parameters of healthy volunteers (28 males and 27 females, aged 20-57 years) who were free from occupational exposure inducing neuropathy were determined by monitoring skin temperature. A questionnaire survey on height, alcohol and tobacco consumption was also performed. The following results were obtained: 1) Analysis of covariance to examine the relation between age groups and NCVs adjusting for skin temperature showed significant differences only in peroneal motor distal latency (MDL) and duration of sural sensory nerve action potential (SNAP) between age groups. However, there was no constant relation between these parameters and age. Multiple regression analysis showed the significant relationships between age and ulnar MDL and the duration of sural sensory nerve action potential, adjusting for sex, height, weight, BMI, alcohol intake (frequency/week, ethanol equivalent ml/week), tobacco consumption (/day), skin temperature and education years. 2) The skin temperature had significant effects on ulnar MDL, ulnar sensory NCV, duration of ulnar SNAP, sural sensory NCV and amplitude and duration of sural SNAP according to the results of multiple regression analysis and analysis of variance. 3) The body mass index had an independent effect on the ulnar nerve conduction, shortening MDL and the duration of the sensory nerve action potential. 4) Consumption of alcohol and tobacco had no significant relation to nerve conduction velocity in our study. These results show that skin temperature is a major covariate of peripheral nerve conduction and that it is very important to control skin temperature in studies on nerve conduction measurements.