How often a colonoscopy is done is highly dependent on the results of the colonoscopy. If the result of colonoscopy is normal, you only need to do 1 colonoscopy in 5 years, but if the colon polyps found by colonoscopy, the time of colonoscopy depends on the number and diameter size of colon polyps. If the polyp found by colonoscopy is single and the diameter of the polyp is 2cm or less, it needs to be reviewed once a year. If the polyp is negative twice in a row, it can be rechecked once every 3 years. However, if there are multiple polyps, or the diameter of a polyp is larger than 2cm, the colonoscopy should be repeated every 0.5 years, and if the results of two consecutive colonoscopies are negative, the colonoscopy can be repeated every 1 year.