Colorectal cancer has been rapidly increasing in Korea during the past decades, which was known as low risk area. The age-standardized mortality rates increased from 3.0 to 14.5 in 100,000 for men and from 2.3 to 7.9 in 100,000 for women between 1983 and 2008. According to the National Cancer Registry, the age-standardized incidence rates of total colorectal cancer were increased by 7.3% and 5.5% for men and women, respectively, between 1999 and 2005, while the incidence rates of the most prevalent cancers in Korea, such as stomach, liver, and cervical cancers, have decreased during the same period. Westernized dietary and lifestyle-related factors seem to be closely related to the increased risk of colorectal cancer. Higher intakes of red and processed meat, a lack of physical activity, obesity, and alcohol drinking have been suggested to be risk factors for colorectal cancer in the numerous epidemiologic studies, while higher intakes of dietary fiber, green leafy vegetables, some micronutrients abundant in vegetables and fruits, such as folate, and calcium were reported to be protective factors. Since many of the diet and lifestyle-related factors for colorectal cancer are modifiable, it is urgently needed to set up comprehensive primary prevention program against colorectal cancer to effectively cope with the rapidly increasing cancer in Korea.