Three hundred and thirty one patients with cancer of the rectum and rectosigmoid junction, operated on during the period 1968-1985 are here examined. The study shows the prognostic value and the impact that stage, histopathological grade, number and location of nodal metastases, morphology of the primary tumour, occurrence of obstruction, perforation, and haemorrhage have on the natural history of the tumour. Stage and histopathologic grading resulted as the most outstanding prognostic parameters also because they are correlated to the presence, number, and location of nodal metastases as well as occurrence of obstruction, perforation and haemorrhage. The study concludes that: a) stage according to the Dukes-Gabriel classification still has a reliable prognostic predictivity, since it faithfully reflects major anatomic situations observed in rectal cancer; b) Dukes' stage C cases should be considered as a non-homogeneous group with a distinct biological behaviour depending on the number and site of the lymph nodes involved; c) intraoperative staging of the tumour, if possible, should guide the excision extent on a curative aim, where the term means a prospective evaluation based on statistical data correlating stage and survival.