Morphometric evaluation of adenomas of the colon to determine their degree of dysplasia is still controversial, since subjective factors influence the decision concerning benignancy or malignancy. Some indices have been proposed to assist in categorizing intermediate lesions into benign or malignant. However, these indices show a wide range of distribution. To evaluate the reliability of one such index, the index of structural atypism (ISA, area of glands/area of stroma), we studied polyps as a whole, and found great variability of index values within a single polyp.