Fifty-nine colo-rectal polyps were detected at endoscopy and repeatedly biopsied before removal by endoscopic snare polypectomy. The aim of the present paper was to evaluate the reliability of multiple forceps biopsies in assessing both the malignant potential and the presence or absence of invasive cancer (IC) in colo-rectal adenomas (CRA). In order to achieve the first objective, the histologic types and the degree of dysplasia have been defined. The data obtained by means of multiple biopsies examination, compared with those of polyp in toto study, show that fractional biopsies were of value in the histologic classification of only the smallest 41 polyps (agreement 88.09%), whilst no reliability of biopsies was demonstrated in the 18 largest polyps (agreement 27.68%). In the field of dysplasia grading, the agreement was 55% and 61% for the smallest and the largest CRA respectively. These last figures are hardly acceptable. Biopsies examination gave also under- and overestimation of the histologic severity and of dysplasia as well as a significant incidence of false negative results in IC detection. It is concluded that polypectomy is the only method which provides adequate material for precise diagnosis, no matter how large a polyp. Therefore it should be performed whenever possible. Finally the authors discuss the management of small sessile adenomas.