This is an analysis of 23 patients with clinically and/or surgically unresectable adenocarcinoma of the rectum on initial evaluation who were treated with preoperative irradiation and surgery between March 1970 and April 1981. All patients have had follow-up for at least 5 years. Five patients (22%) had exploratory laparotomy and diverting colostomy before irradiation. All patients were irradiated with megavoltage equipment to the pelvis at 180 rad/fraction, continuous-course technique. Total doses ranged from 3500 to 6000 rad with a mean of 4800 rad and a median of 5000 rad. All patients had surgery 2-11 weeks (mean: 4.9 weeks; median: 4 weeks) after radiation therapy. Twelve patients (52%) had lesions that were incompletely resected because of positive margins (7 patients), distant metastasis (1 patient), or both (4 patients). All of these patients died of cancer within 5 years of treatment. Eleven patients had an apparent complete excision of their rectal cancer; six patients (55%) subsequently had a local recurrence. The 5-year absolute survival rate for patients who had complete resection was 18% (2 of 11 patients). The 5-year absolute and determinate survival rates for the entire study were 9% (2 of 23 patients) and 9% (2 of 22 patients), respectively. One patient (in the incomplete resection group) died after operation secondary to sepsis and diffuse intravascular coagulation.