The same region of intestinal ileum was compared in the same rats at 10 and 20 wk of age to determine if reported differences in vessel density between these ages were the result of changes in vessel numbers. The number and branching pattern of arterioles observed remained remarkably constant during the 10 wk between observations, and minimal enlargement of bowel mass occurred. No significant change in average maximum diameter of arterioles was observed. Although the total number of small arterioles did not change, vessels were gained and lost at an equal rate (7%) between 10 and 20 wk. There was no significant changes in means or frequency distributions of intercapillary distances in the radial or longitudinal bowel muscle layers. The results indicate that the intestinal microvascular branching pattern changes very little from juvenile to adult life. However, a slow turnover of small arterioles does occur, indicating an ongoing remodeling of the terminal vasculature during juvenile life.