AbstractElectrodiagnostic evaluation of diaphragmatic function has consisted of phrenic nerve stimulation and surface or esophageal recordings of the electrical activity of the diaphragm. Needle electromyography of the diaphragm has rarely been reported because of the perceived danger of this procedure. We describe a new technique for needle electromyography of the diaphragm. Am EMG electrode is placed in the costal insertion of the diaphragm under the 8th, 9th, or 10th rib cartilage, distant from the major vessels, pleura, lungs, and abdominal viscera. Diaphragmatic denervation was found in 42 of 81 patients using this method. There were no complications related to the procedure. Needle electromyography of the diaphragm provides important information in the diagnosis and management of respiratory dysfunction. © 1993 John Wiley&Sons, Inc