Motility disturbances following prolonged intestinal obstruction have been attributed to secondary effects. This study aimed to demonstrate the effects of incomplete obstruction on the enteric nervous system (ENS) of a rat model. Surgical placement of a nonstrangulating ligature encircling the distal bowel was performed in 41 freshly weaned rats. Anesthetic protocol included Ketamine, ether, or Xylazine (an alpha 2-adrenergic agonist). Histological evaluation was by ganglion cell morphology, histochemical staining for acetylcholinesterase (AChE) and tyrosine hydroxylase (TOH) immunocytochemistry. Forty-one freshly weaned LE rats were divided into controls (8), sham procedures (8), intestinal obstruction (16), and a group of rats with colonic biopsy performed prior to and following experimental obstruction (9). The rats were sacrificed at periods varying between 14 and 45 days post experimental obstruction (median survival, 27 days). Histological changes included elongation of ganglion cells and a decrease in the number per 5-mm slide in obstructed animals. No other obstruction specific differences were detected. A significant (P < .01) increase in AChE in the submucous plexus was recorded in Xylazine-anesthetized animals. No obstruction-specific effects could be demonstrated in the ENS, suggesting that prolonged obstruction without ischemia does not result in any significant alterations in the ENS. Pharmacological stimulation of the alpha 2-adrenergic receptor appeared to result in an increase in AChE. This mechanism may help to explain a possible role for the adrenergic system in the increased AChE levels in affected bowel in patients with Hirschsprung's disease.