Fifty-two local recurrences (LR) of colonic (n = 31) or rectal (n = 21) cancers, with synchronous metastases in 19 cases, were treated aggressively between 1981 and 1989. Treatment consisted of extended surgical resection combined with transcutaneous radiation therapy. Intravenous chemotherapy (5 fluorouracil and folinic acid) was delivered to the last 42 patients. The synchronous metastases were resected in all cases, except one. A sufficient high-dose radiation therapy (45 Gy after complete excision and 60 Gy after incomplete excision) was performed in 23 cases only. The majority (29 cases) of the patients underwent a second operation, and some 3, 4, or 5 operations. Global survival and survival without recurrence were 60 percent and 42 percent at 3 years. These good results were not stable and decreased progressively with time. The excision required usually surgery of large magnitude. Postoperative mortality was null but morbidity and functional disorders were important. After complete excision of the LR, radiation therapy doubled the rate of local control when it was greater than 45 Gy. The benefit of radiation therapy was doubtful after incomplete excision, even with high-dose irradiation. The role of systemic chemotherapy could not be analyzed in this study. Study of prognostic factors showed that resectable synchronous metastases and rectal or colonic location of primary tumors were not correlated with survival, Survival was correlated with the local control of LR (P = 0.012) and the presence of invaded neighbouring organs (P = 0.006) which reflected the tumor volume. In conclusion, it was difficult to conclude if aggressive treatment of LR should be mandatory or not.(ABSTRACT TRUNCATED AT 250 WORDS)