Here, we report a case of Cronkhite-Canada syndrome in a patient with schizophrenia. A 64-year-old man, who had been diagnosed as having a schizophrenic disorder at the age of 30, presented with alopecia, atrophic nail changes, hyperpigmentation of the skin, and inflammatory polyposis of the stomach and colon. Endoscopic ultrasonography of the stomach and colon revealed diffuse mucosal thickening with small hypoechoic areas, corresponding to edema of the lamina propria. After treatment with parenteral hyperalimentation and tranexamic acid, his physical findings and polyposis gradually improved. This is the first report of Cronkhite-Canada syndrome in a patient with schizophrenia.