Crohn's disease of the terminal ileum recurs in a predictable sequence proximal to the ileocolonic anastomosis after surgical resection. To confirm the suspicion that the duration of recurrent ileitis correlates with the extent of presurgical disease, this study investigated 23 consecutive patients with recurrent Crohn's disease symptoms who had undergone ileocaecal resections between 1982 and 1992 at our institution and had both preoperative and postoperative small bowel follow through studies available for comparison. All films were reviewed by a blinded gastrointestinal radiologist using uniform criteria. Symptomatic recurrence was reported at a mean (SEM) of 29 (25) months after resection. Presurgical length of inflammation averaged 26 (15) (8-57) cm and at recurrence 24 (14) (7-55) cm. The correlation coefficient (r) between pre and postsurgical extent of ileal disease was 0.70 (p < 0.0001). Seven patients had sequential small bowel series after 20 (10) (7-36) months without intervening surgery. The extent of measured inflammation between examinations correlated with r = 0.995 (p < 0.0001), showing the consistency of the measurement process. The close correlation between the duration of postoperative recurrence with the extent of presurgical disease is another example of individual patterns of recurrent Crohn's disease and is an additional factor to be considered when contemplating surgical resections.