BACKGROUND: The reference values of laboratory should review regularly to maintain good quality of practice. This is the second report of studies on reference values of Korea Association of Health Promotion (KAHP). The first one was reported in 2002 in Journal of Laboratory Medicine and Quality Assurance in Korea. The aim of this study is to know the changes of reference values for the past five years. METHODS: The way to analyze the data this time was essentially the same as the previous one (Indirect Method). The data from January to December, 2007 were collected. They totalled 5,133,327 test results from approximately 140 thousands individuals who visited for health checkup. The data were statistically analyzed with Minitab version 22.214.171.124 for Gaussian distribution using Anderson-Darling test. The trimming process repeated for the outliers, the results lying outside of +/-3SD, and as much as four times in certain test items, though, none of the tests showed Gaussian distribution. Subsequently, the reference values of most tests were defined in the ranges from the point of lowest 2.5% to the point of highest 97.5% and others were those, below 95 percentiles according to CLSI C28-A3 guideline. RESULTS: The reference ranges of 56 test items were either set as before or adjusted with new values, and compared. CONCLUSIONS: Comparing to the previous reference values (2002), the tests for liver function showed the lower upper values and the tests for diabetes and lipids showed higher upper values. Others were changed minimally with no significance.