A series of 177 patients with recurrent colorectal cancer treated at the Massachusetts General Hospital is examined retrospectively. Two thirds of recurrences were observed by the second postoperative year, and 15% of patients were asymptomatic. Pelvic recurrences were usually attributable to rectal or sigmoid tumors, whereas right-sided carcinomas frequently spread to the liver. The commonest methods of clinical discovery of recurrence included findings of abdominal and pelvic masses, hepatomegaly, and positive chest films. The average survival after discovery of recurrence was only eleven months, but 23 patients having reresections for cure lived an average of thirty-three months. Seven patients (30%) undergoing reresection for cure represented probable cures. Chemotherapy with intravenous 5-FU provided poor palliation, but radiotherapy gave satisfactory relief of symptoms in approximately 50% of patients, particularly those with rectal or low colon lesions. A program of follow-up is offered since there is evidence that even the symptomatic patient may be well palliated or even cured by surgical resection of the recurrence or palliative therapy.