A new method for comparing the effects of small and large intestinal mechanical stimulation was developed. Isolated intestinal loops were created by the Thiry-Vella method from the lower duodenal--upper jejunal, and from the upper colonic portion of the gut, respectively. This preparation allows parallel evaluation of stimulation effects and affects from both the small and the large intestine of the same animal. A balloon could be inserted into the isolated loops before each experimental session and removed afterward. Behavioral thresholds to changes in the volume of the gut were recorded and compared in the two loops. No essential differences between the two portions of the intestinal tract were detected by this method.