Since 2004, the National Cancer Screening Program (NCSP) for colorectal cancer has provided annual screening by fecal immunochemical test (FIT) for individuals aged 50 years or older in the Republic of Korea. This study was conducted to investigate trends in the participation rate of the NCSP for colorectal cancer overall and according to gender, age and health insurance type. Therefore, we analyzed participation, positivity, and follow-up rates according to these factors. Overall participation rates for the NCSP for colorectal cancer increased from 10.5% in 2004 to 26.2% in 2009. FIT positivity rates decreased from 7.9% in 2004 to 7.1% in 2009. Follow-up rates among FIT-positive participants decreased from 64.5% in 2004 to 39.4% in 2009. Although the participation rate increased each year during the study period, it remained low compared with that of other countries. The FIT positivity rate decreased, however it was relatively high compared with that of other countries. Intervention is essential to raise participation rates, maximize adherence to screening recommendations, and to make certain that all population subgroups reap the benefits of screening. Also, these data suggest that structured and standardized quality improvement activity is essential to high quality for FIT in the NCSP for colorectal cancer screening in Korea.