In 11 patients with chronic inflammatory demyelinating polyneuropathy (CIDP) and 11 patients with chronic idiopathic axonal polyneuropathy (CIAP), absent myotatic reflexes were significantly associated more often with CIDP than with CIAP, an absent biceps-reflex having the highest sensitivity and specificity for the diagnosis of CIDP. In CIDP, the latencies of electromyographically recorded myotatic reflexes often indicated demyelination, notwithstanding normal clinically assessed myotatic reflexes. Myotatic reflexes may therefore be useful for the distinction between axonal and demyelinating polyneuropathy.