In 23 cases of surgically resected superficial esophageal cancer which was defined by Japanese Society for Esophageal Diseases, the nuclear area (NA), nuclear shape factor (NSF) and DNA content (DNA) of cancer cells were measured using an image analysis system, and, in 7 out of the 23 cases, biopsy specimens were examined in the same way as well. The results were analyzed and evaluated with respect to lymph node metastasis. The NA was significantly larger (p less than 0.01) and the DNA content value was significantly higher (p less than 0.05) in the tumors with lymph node metastasis than in those with no lymph node metastasis. By means of a linear discriminant analysis using NA and DNA as variables, z = 0.238 X NA + 0.475 X DNA - 11.9, existence of lymph node metastasis could be correctly presumed at 87%. No false discrimination was found on preoperative biopsy specimens in 7 cases in which the accuracy of the discriminant analysis could be confirmed by microscopic examination of the lymph nodes extirpated at operation for esophagectomy. Conclusively NA and DNA correlate significantly with existence of lymph node metastasis in the patients with superficial esophageal cancer, and might be useful for preoperative predicting whether or not lymph node metastasis exists.