In the clinical laboratory medicine,the measurement uncertainty (MU)is a relatively new concept.Over the years, experts of clinical laboratory medicine from all over the world made a great number of further researches and promote the development of MU,which led clinical laboratories to pay more and more attention to the meanings and functions of MU at the same time.However,because of the habitual using of the total error (TE)in clinical laboratories and similarities between concepts of MU and TE which easily resulted in confusion,a lot of laboratories still cannot completely accept MU.By explai-ning concepts of TE and MU and analyzing the pros and cons of models of TE and MU as well as their functions,the obj ec-tive of this paper is to help clinical laboratories make further comprehensions of TE and MU and understand how to properly use them in practice.