Abstract: Traceability is essential for standardization and harmonization of clinical analytical results. The measurement result can be comparable to a reference through a documented unbroken chain of calibrations each contribution to the measurement uncertainty. Reference measurement procedure defined as providing measurement results fit for intended use in assessing measurement trueness of measured quantity values obtained from other measurement procedures for quantities of the same kind. Isotope Dilution Mass Spectrometry is a primary standard acknowledged as having the highest metrological qualities and whose value is accepted without reference to other standards. The review focused on the applications of IDMS in clinical reference measurement system including its principle, quantitative approaches and its related uncertainty. The updated status of JCTLM database was also commented in this review, which is helpful for those related researchers in clinical measurement, isotope application as well as metrological fields.