Prognostic factors that may alter the indications for primary surgical resection or that can be influenced by the extent of the procedure were analysed in a homogeneous group of 186 patients with squamous cell carcinoma of the oesophagus. All patients underwent standardized en bloc oesophagectomy and lymph node dissection with prospective documentation of the histopathological findings; follow-up was complete. Multivariate analysis identified the Union Internacional Contra la Cancrum R category (i.e. the presence of residual tumour after resection) as the most important independent prognostic factor (P< 0.001) followed by the ratio of invaded to removed lymph nodes (P< 0.001). These data suggest that only patients in whom R0 resection can be anticipated based on preoperative assessment should undergo primary resection for oesophageal cancer. Extended lymphadenectomy may improve survival in patients with a limited number of invaded mediastinal nodes.