The purpose of this study was to analyze the neuronal density of the myenteric plexus of the intermediate and antimesocolic regions of the descending colon of rats. Whole-mounts were stained with three different techniques of neuronal evidenciation. Through counts of the number of neurons in an area of 6.64 mm under light microscopy, we found 1,271 +/- 227.54 neurons with Giemsa in the intermediate region and 1,234 +/- 225.92 neurons in the antimesocolic region; with the NADH-diaphorase technique we found 530 +/- 92.97 neurons in the intermediate region and 539 +/- 146.72 neurons in the antimesocolic region; and through the NADPH-diaphorase histochemistry, we found 417 +/- 34.42 neurons in the intermediate region and 547 +/- 84.01 neurons in the antimesocolic region. We conclude that there is a variation in the density of NADPH-diaphorase positive neurons in the intestinal circumference; that the NADH-diaphorase positive neuronal subpopulation represented 42.7% of that stained with Giemsa; and that the NADPH-diaphorase positive neurons represented 37.8% of the whole myenteric population.