During a 25-year period, four patients with esophageal diverticulum associated with carcinoma of the esophagus underwent surgery. The results were satisfactory. The clinical features included a long history of diverticulum and the presence of a carcinoma of the esophagus in close proximity to the former. Inflammation within the diverticulum and in the mucosa around the diverticulum was noted. The closer the diverticulum to the carcinoma, the more severe the inflammation. Therefore, diverticulitis and esophagitis may be important factors leading to the development of carcinoma of the esophagus, and patients with esophageal diverticulum should be followed up regularly and the diverticulum resected as early as possible if inflammation within the diverticulum or peri-diverticular esophagitis is found.