Nationwide incidence survey was conducted to estimate the annual incidence rates of colorectal cancer among Koreans between Jan 1, 1988 and Dec 31, 1989. The population of the incidence survey was the beneficiaries of Korea Medical Insurance Corporation (KMIC), which were about 4,500,000 persons. The medical records of patients with diagnosis of either ICD-9 153(colon cancer), 154(rectal caner), 197(secondary malignant neoplasm of digestive and respiratory system), or 211(benign neoplasm of digestive system) were abstracted for the period with the standard format. The diagnosis was confirmed by one oncologist through the review of these abstracts. The numerator of the rate was finally defined as the incident colorectal cancer cases diagnosed between July 1, 1988 and June 30, 1989. The crude annual incidence of colorectal cancer for men was 13.1 per 100,000 and 10.6 for women, which was still low when compared with those of Japan and China during the same period. Age-adjusted sex ratio was 1.2 for right-sided colon cancer and 1.9 for left-sided colon cancer. The excess of right colon cancer among postmenopausal women was remarkable, so further analytical approach would be needed to investigate which factors are related with this phenomenon.