We have investigated the motility effects of acute experimental canine intestinal obstruction. A 30-min midjejunal obstruction was produced by clamping a Biebl loop or by inflating an intraluminal balloon. Spike bursts from serosal electrodes proximal to the site of obstruction increased markedly, while those from distal electrodes decreased. When the obstruction from an intraluminal Foley catheter was continued for 5.5 h, the inhibition persisted distally but the proximal contractile activity gradually fell to control levels. The reduced proximal activity after prolonged obstruction was largely due to clusters of regular intense spike bursts preceded and followed by lengthening periods of absent motor activity. Similar clustered contractions obliterated the lumen when the passage of barium through a Thiry-Vella loop was monitored fluoroscopically. Significant motility changes occur in intestinal obstruction, but an increased understanding of the mechanisms involved awaits future studies.