Abstract Cronkhite–Canada syndrome (CCS) can be difficult to diagnose. To diagnose CCS, it is important to perform endoscopic examination for patients with chronic diarrhea, check for the presence or absence of polyposis, and evaluate inflammation in the mucosa between the polyps. This study reported seven cases of CCS. The age of the patients, which included four men and three women, ranged 48–72 years, and all patients were Asian. The most common symptom among these patients was chronic diarrhea. Three of the patients had rectal cancer. In two patients, the lesions were detected at an early stage and resected via endoscopic treatment. CCS is associated with a high risk of malignant gastrointestinal lesions, especially rectal cancers, and periodic surveillance endoscopy and careful observation are required.