The length and radiologic type of tumor, esophageal axis and azygogram were examined in 208 patients with carcinoma of the thoracic esophagus who underwent esophageal resection from 1965 to 1975. An histologic examination was performed on all resected specimens. These examinations were used as diagnostic aids to determine the resectability of esophageal carcinoma before surgery. Tumor length did not seem an adequate parameter on deciding resectability; nor did the radiologic type of tumor. Examination of the esophageal axis was in determining resectability. The azygogram gave the most accurate information about resectability of these 4 parameters. The probability of a correct diagnosis regarding differentiation of noncurative a3 lesions from other resectable lesions was 85.6%.