Histological preparations of the rectal mucosa were analyzed quantitatively in 61 patients with ulcerative colitis in remission (UCR). Four histological variables were recorded: the diameter (minor axis) of the lumen of 10 consecutive (transversally cut) glands, the interglandular linear distance between 10 consecutive glands, the number of glands at high-power field examination, and the number of nuclei in 10 consecutive areas of lamina propria. The most important feature to differentiate UCR patients from non-colitic patients was the distance between glands and the number of glands per area. The sum of the values of the four variables demonstrated that 84% of the patients with UCR had scores of 22 or more, whereas only 1 of 124 non-colitic patients (that is, 0.8%) had similar scores.