Large surgical series are agreed on the fact that the prognosis for radically operated colorectal cancer has improved little in the last twenty years. Reasons for these failures are, of course, local or remote recurrences. To improve the number of stable cures, experiments have been carried out with complementary or coadjuvant techniques whose purpose is to limit intra-operative dissemination of the tumour and to monitor the number of cancer cells that might remain after radical surgery. Such techniques have been applied at preoperative, intra-operative and post-operative phases. Results obtained so far have been uncertain but seem to point to the usefulness of intraoperative procedures in reducing the number of local recurrences and of postoperative chemotherapy with 5 FU which has improved five-year survival indices by 5-7%.