A case of diffuse leiomyomatosis of the esophagus which was successfully resected is presented. The patient was a 44-year-old man who had an abnormal filling defect, which was incidentally discovered during esophagography, and was observed for two years. Although he remained asymptomatic, an operation was performed because of increase in the tumor's size. The lesion consisted of many confluent myomatous nodules throughout the thoracic portion of the esophagus, mostly seen in the circular layer of the muscularis, and some in the muscularis mucosa. Histologically, these nodules were leiomyomas. This is a very rare condition, and only a dozen similar cases have been reported so far. A brief discussion is made on the definition of diffuse leiomyomatosis of the esophagus.