Small bowel anastomoses were made in a group of adult Sprague-Dawley rats. In another group of animals, interrupted suture of the terminal ileum was performed without transection. The animals were labeled repeatedly by injections of 3H-proline during the second and third week after surgery. Animals were sacrificed at three weeks after anastomosis or suturing. Ten and two mm segments were precisely excised on either side of the anastomoses or suturing. Total collagen and total radioactivity were measured per length of segment. In the small intestine, a similar increase in collagen (four-fold) and its radioactivity (four-fold) occurs only within a centimeter of the anastomotic site, mostly within 0.4 to 0.6 mm. Some of this increase in secondary to the effects of the suture, but most of the increase is due to the anastomosis. The collagen data indicate that the healing of a small intestinal wounds is a local phenomenon.