Twenty-three patients with small intestinal Crohn's disease were studied by barium-methylcellulose infusion. All patients underwent surgery within 1-24 months (average 7 months). The extent of the lesions and the small bowel length were radiologically evaluated by means of a map measurer. The same measurements were performed at surgery. Radiological and surgical data concerning the extent of enteritis were statistically correlated (r = 0.7). The correlation between radiological and surgical measurements of total small bowel length was not significant.