Between 1979 and 1988, 33 patients with squamous cell carcinoma of the anal canal were treated with chemoradiation. There were 24 women and 9 men, from 37 to 90 years of age (median: 63 years). Complete tumor regression occurred in 29 of the 33 patients (88%), only one of whom later developed recurrence. In the other four patients, there was persistent tumor after 3 months; three of these patients died within 2 years; and one is alive with distant metastases 2 years later. During the first 5 years of the study, seven patients with complete tumor regression underwent planned abdominoperineal resection following chemoradiation. Four of the abdominoperineal resection specimens were free of tumor, but three were not. These three patients, who had abdominoperineal resection within 3 months of chemoradiation, are disease-free. Ten of the 29 patients who had complete tumor regression had biopsies of the primary site 3 months after treatment. All biopsies were negative for residual carcinoma. At present, 26 patients (79%) are alive and disease-free from 2 to 10 years post-treatment (median: 4 years). Two patients died of unrelated causes, four of cancer, and one is alive with cancer. Complications of the chemoradiation required surgical intervention in two patients, and two others developed severe hematologic toxicity, for a complication rate of 12% (4 of 33 patients). There was no treatment-related mortality. These results support the efficacy of chemoradiation treatment for carcinoma of the anal canal. They suggest that abdominoperineal resection no longer need be part of the planned initial management, and that posttreatment biopsy of the primary site is unnecessary, unless palpable or visible abnormalities are present 3 months after treatment.