Surgical interruption of the gastrointestinal tract is widely used for investigating the structure of the enteric nervous system and in the treatment of certain pathological conditions of the gastrointestinal tract. The effects of transection and end-to-end anastomosis and myotomy on nerve cells of the myenteric plexus were studied by light and electron microscopy, 1, 2 and 6 wk postsurgically. During the 1st wk, degeneration of some nerve cells was indicated by the dilatation of the endoplasmic reticulum and dispersion of Nissl substance. The degenerative process (an early electron-dense lamellar degeneration and a late floccular degeneration) was accompanied by some regenerative changes during the recovery period. Quantitative light microscopic analysis demonstrated a significant decrease in the number of neurons located 1 and 5 mm from operation sites in the intestine.