In axonal polyneuropathy, the loss of nerve fibers of different sizes and velocities results in a small compound muscle action potential (CMAP) with preserved biphasic and smooth waveform. In acquired demyelinating polyneuropathy, the demyelinating process is patchy and affects the peripheral nerve fibers randomly. There is no simple rule for determining the number of nerve conduction studies (NCSs) that should be performed in a patient with polyneuropathy. A patient with sensory and motor symptoms in the hands and feet came to the electromyography (EMG) laboratory for evaluation of polyneuropathy. One of the most important roles of EMG in the evaluation of polyneuropathy is to categorize patients into a primary axonal or primary demyelinating polyneuropathy. In addition to acquired primary demyelinating polyneuropathy, another treatable peripheral nerve disorder that neurologists and electromyographers should keep in mind at all times is vasculitic neuropathy.