This study examined the influence of tumour involvement of the circumferential resection margin on subsequent local recurrence after oesophagectomy. Fifty patients were studied: 36 men and 14 women of median age 62 (range 44-83) years. Each patient had undergone oesophagectomy at which all macroscopic disease had been removed. Pathological specimens were sectioned tangentially at 0.5-1.0-cm intervals to permit microscopic examination of the circumferential resection margin. Patients were followed and investigated by endoscopy with biopsy and imaging techniques only if symptomatic. Twenty of the 50 specimens demonstrated involvement of the circumferential resection margin. At median follow-up of 36 (range 24-52) months, eleven of these 20 patients had developed histologically proven local recurrence compared with only four of the remaining 30 in whom the resection margin was clear of tumour (P < 0.01). Circumferential spread of oesophageal cancer appears to be a significant cause of local tumour recurrence.