A careful histopathological analysis was performed on a series of 244 unselected surgically removed primary colonic and rectal cancers. Tumours were staged according to the TNM system. Tumour type (adenocarcinoma or mucinous carcinoma), grade of differentiation, character of invasive margin, degree of peritumoural lymphocytic infiltration, venous and neural invasion were found to be correlated with the clinico-pathological stage and in some ways interrelated. As a whole our results seem to suggest that histological evaluation of the variables examined may provide information of clinical relevance in the management of patients with large bowel cancer.