Optimal application of the nerve conduction study depends on an understanding of the principles and a recognition of the pitfalls of the technique. The conventional methods deal primarily with distal nerve segments in an extremity. Other techniques allow one to assess nerve segments in less accessible anatomical regions, to improve the accuracy in precisely localizing a focal lesion, and to increase sensitivity in detecting subclinical abnormalities. Despite certain limitations, these methods can provide diagnostically pertinent information if they are used judiciously in appropriate clinical contexts. I wish to review the fundamental concepts of nerve stimulation techniques and their proper applications in the clinical domain. The discussion primarily relates to the importance of reproducibility of various measures and pitfalls in the evaluation of conduction block.