Three hundred twenty patients with rectal cancer were studied to determine factors that correlate with development of pelvic recurrence. The mean age was 65 years; anterior resection was performed in 202 (63 percent) and abdominoperineal resection in 118 (37 percent). Fifty-two patients (16 percent) developed pelvic recurrence. The mean duration of follow-up to development of pelvic recurrence was 22 months. Depth of tumor invasion, presence of lymph node metastasis, and colloid features were found to correlate with pelvic recurrence. The recurrence rate in patients having anterior resections was the same as that of patients undergoing abdominoperineal resections. Patients having anterior resection with distal margins of 1 cm or less had an extremely high recurrence rate (36 percent). Pelvic recurrent did not continue to improve when the distal margins were extended over 2 cm. Microscopic lateral tumor extension, which is not removed during operation, appears to be the major determinant of local recurrence in rectal cancer.