AbstractChanges of the terminal innervation pattern in polymyositis were studied in nine patients using single fiber electromyography (SFEMG) and histochemical investigations of muscle biopsies. In all patients, and in 16 out of 18 muscles studied, reinnervation was found. The preceding denervation could be caused either by segmental necrosis of the muscle fiber that disconnects one part of the fiber from the end‐plate region or by direct intramuscular nerve involvemen