Objective To explore the endoscopic features and careinoembryonic antigen (CEA) ex-pressions of colorectal serrated adenomas (SA). Methods From June 2005 to July 2008, 27 patients with colorectal polyps and 26 cases of advanced colorectal cancer (ACC) were enrolled in the study. The pit pat-tern of the suspected lesions were observed with 0. 4% indigo carmine sodium stain and classified according to Kudo classification. The polyps were removed by biopsy, high-frequency electrical excision or endoscopic mucosa resection and the samples of ACC were collected with biopsy forceps. All specimens underwent rou-tine pathological examination and CEA expression was detected by immunohistochemistry. Results There were 47 SAs and 27 other types of polyps in polyp group. Most SAs located in left-side colon and were char-acterized by the bulge semipedunculation. The diameters of 45 serrated adenomas ranged from 3 to 8ram, and the maximal diameter of other 2 were more than 10ram. The most common type of pit pattern in SA was mixed type Ⅱ and ⅢL, with type Ⅱ predominant in a certain percentage. Expression of CEA in SA glands was significantly higher than that in proliferative polyps (P < 0. O1). Candnsion SA is an unique type of colorectal adenoma, which is capable of expressing CEA, and displays malignant potential and deserves great attention.