Laterally spreading tumor (LST) originates from the large intestine mucosa with prominent lesions that mainly extend laterally other than vertically. The pathological morphology and evolvement of this disease distinguish itself from other adenomas, and its close association with colorectal cancer has been noted. Up till now, no report on LST involving the large intestine has been available in China, therefore we presently report our experience in the diagnoses and treatment of 25 LST patients (26 lesions) identified with conventional endoscopy and mucosa staining during the period from Nov, 2000 to Oct, 2001. Among the 26 lesions, 11 were classified into granular homogeneous type, 15 into nodular mixed type, and 3 patients were found to have intramucosa carcinoma and 2 serrated adenoma. The biggest lesion was 60 mmx70 mm, the smallest being 11 mmx12 mm, and 6 lesions were within the range of 11 to 20 mm, 9 within 21 to 30 mm with the rest 11 lesions exceeding 31 mm in diameter. Type IV pit pattern was predominant in the the 26 lesions, accounting for a proportion of 61.54% (16/26). Two lesions with V(A) pit pattern and 1 with IV pattern were pathologically diagnosed to be intramucosa carcinoma, and 8 with type III(L) pit pattern were tubulovillous adenoma. Immediate or elective endoscopic mucosa resection or partitioned mucosa resection was performed in the 25 cases without incidences of the complications as bleeding or perforation.