This paper examines the hypothesis that a reduction in the distal mural margin during anterior resection for sphincter conservation in rectal cancer excision is safe, provided total mesorectal excision is undertaken with wash-out of the clamped rectum. One hundred ninety-two patients underwent anterior resection and 21 (less than 10%) patients underwent abdomino-perineal excision (APE) by one surgeon (RJH). Anterior resections were classified as "curative" (79%) and "non-curative" (21%); in the "curative" sub-group less than 4% of patients developed local recurrence. The series was retrospectively analyzed for the effect of mural margins on local recurrence with 152 patients undergoing "curative" anterior resections and 40 patients undergoing "non-curative" resections. In the 152 specimens from curative resections, 110 had a resection margin greater than 1 cm and 42 had a resection margin less than 1 cm. Four patients developed local recurrence in the greater than 1 cm margin group (95% confidence interval: 0.8%-7.8%) and no patients developed local recurrence in the less than or equal to 1 cm margin group (95% confidence interval: 0%-5.9%). In each patient with local recurrence a cause for failure was apparent. There was no statistically significant difference in local recurrence rate between the less than or equal to 1 cm margin group and the greater than 1 cm margin group. A reduction in resection margin therefore did not compromise survival after anterior resection. The significance of lateral resection margins is discussed. The role of deep radiotherapy and cytotoxics are considered.(ABSTRACT TRUNCATED AT 250 WORDS)