Objective: One of the important parameters in the electrodiagnosis is the nerve conduction study (NCS) which is calculated from two other variables,i.e distance and time. Therefore, appropriate measurement of these variables which are the base of proper diagnosis is obviously very important. In this study, these was an attempt to evaluate and compare nerve conduction responses in the two methods of measuring distances with tape and caliper to show which one is more reliable than the other one.

Methods: This study was carried out on 100 hands of 50 appearantly healthy volunteer medical students. They were examined for the NCS of the median and ulnar nerves at the wrist using a nylon tape and a caliper. Reliability value, Cronbach`s alpha and the mean of the inter-time differences were calculated for each method.

Results: The means of inter-time difference, Cronbach`s alpha and reliability values for all the variables were more significant in the caliper measurement especially for nerve conduction velocity (NCV) parameter.

Conclusion: Caliper seems to better estimate the actual length of nerve conveying the electrical impulse and better accommodate with actual course of the nerve under the skin. Therefore, using the caliper for measuring the distance might be more reliable than the routine method of tape measurement.