Pathologic findings in 21 esophagectomy specimens from patients having preoperative combined intracavitary radiotherapy (ICR) and external-beam radiotherapy (EBR) are described. Eleven patients received 1500 cGY ICR and 4000 cGy EBR (Group 1) and ten patients received 1500 cGy plus 2000 to 3000 cGy EBR (Group 2). Effectiveness of radiotherapy was expressed as the ratio between depth of radiation effect and depth of tumor invasion. Depth was expressed as one of four levels: Level I, not deeper than the muscularis mucosa; Level 2, involving but not deeper than submucosa; Level 3, involving but not deeper than muscularis propria; and Level 4, involving periesophageal soft tissue. The depth of radiation damage to tumor cells was comparable between the two groups. However, residual tumor was present in the periesophageal tissue in only one of 11 patients after high-dose EBR compared to of ten patients with lower dose EBR (P less than 0.01, chi-square test). A ratio of one between radiation effect and depth of tumor invasion was present in six patients receiving high-dose EBR and one patient receiving lower dose EBR (P less than 0.05). The authors conclude that ICR combined with EBR affords good local tumor control in the majority of patients. Higher doses of EBR give a better radiation effect in deeper layers of the esophageal wall. The ratio between depth of radiation effect and tumor invasion provides a simple and objective approach to the pathologic analysis of esophagectomy specimens.