Agenesis or ectopia of the kidney is frequently accompanied by characteristic malposition of specific portions of the bowel. On the right, the descending duodenum and proximal jejunal loops and on the left, the distal transverse colon and anatomic splenic flexure may occupy the area of the renal fossa. Renal ectopia, particularly in the iliac fossa or lower abdomen, may result in a characteristic mass effect upon or displacement of the ascending or descending colon. These observations are of clinical significance both in uncovering the renal anomaly and in distinguishing these bowel changes from such conditions as internal hernia, malrotation of the intestines, and displacement by a tumor mass or organomegaly. It appears that development of portions of the intestinal mesenteric fixation as well as of the extraperitoneal perirenal fascia are embryologically dependent upon normal ascent of the kidney.