摘要AIM: To analyze the differences of clinical characteristics of colorectal neoplasm including polyps between the elderly and young Thai patients.METHODS: Colonoscopy database from December 2000 to October 2004 was retrospectively analyzed. There were 1822 eligible patients who underwent colonoscopy (with a mean age of 56.6 years). Patients were classified into two groups: the older age group (aged ≥ 60 years;n = 989) and the younger age group (aged ＜ 60 years;n = 833). Data were recorded on age, colonoscopic indications, tumor location, colonoscopic findings and their related histological findings.RESULTS: Colorectal malignancy related lesions were more often found in the older age group (21%) than in the younger age group (12%). Left-sided lesions were detected more commonly than right-sided in both age groups in approximately two-thirds of all cases.Hematochezia showed greater association with left-sided lesions in the elderly. No relationship was found between age and neoplasm staging and severity.CONCLUSION: The chance of detecting colorectal neoplasm by colonoscopy was higher in the elderly than in the young Thais. However, both groups had the lesions predominantly located in the left side.