The microbial flora associated with carcinoma of the oesophagus was studied in 12 patients. Oesophageal mucosa was biopsied at thoracotomy and cultured under both aerobic and anaerobic conditions. A heavy mixed growth of aerobic and anaerobic organisms was obtained in all patients. One-third of isolates were anaerobic. The flora was of oral origin. The most appropriate antibiotic combination in this study was ampicillin or penicillin with gentamicin and metronidazole.