The results of surgery as sole treatment of colon cancer are summarized before dealing with those of chemotherapy. Curative or palliative chemotherapy remains controverted. The results of single drug treatments and of the conventional protocols with 5-fluorouracil and nitrosoureas have been disappointing. A promising approach is modulation of 5-fluorouracil by folinic acid, with a response rate of up to 45 p 100, and potentiation of 5-fluorouracil by cisplatin. Intra-arterial chemotherapy has been, and still is, an interesting method in liver metastases, but recent studies and the experience acquired with prolonged follow-ups have thrown doubts on some of its results, notably survival. Adjuvant chemotherapy is even more controversial than curative chemotherapy; however, a recent controlled study has yielded favourable results, and the best drug combinations have not yet been tested. It is concluded that cancers of the colon have shown some chemosensitivity, even though it has not reached the same level as that of cancers of other organs.