Objective To evaluate reference intervals consistency of 18 routine biochemistry among mutual recognition labora-tories by analyzing the information of reference intervals of these laboratories in Beijing-Tianjing-Hebei region.Methods Laboratories submitted the data of reference intervals via interval quality assessment(EQA)software which was based on WEB,then the background of the software save the data as Microsoft Excel 2007 document.Finally,the mutual recognition routine biochemical projects,including Kalium(K),Sodium(Na),Chlorinum(Cl),Calcium(Ca),Phosphorus(P),Total protein(TP),Albumin(ALB),Total cholesterol(TC),Triglyceride(TG),Creatinine(CRE),Urea(URE),Uric acid (UA),Glucose(GLU),Alanine amino transaminase(ALT),Aspartate aminotransferase(AST),γ-glutamyltranspeptidase (GGT),Lactate dehydrogenase(LDH)and Creatine kinase(CK)of 56 mutual recognition laboratories were chosen,and perform analysis on upper and lower limits of reference intervals and their sources.Results The sources of reference inter-vals differ among different laboratories.As for projects owning hygiene professional standards(including K,Na,Cl,Ca,P, TP,ALB,CRE,URE,ALT,AST,GGT,LDH,CK),the primary sources were hygiene professional standards(23.1%~48.1%),manufacturer instructions of reagents/instrument(17.3%~41.8%)and National Clinical Laboratory Procedures (18.9% ~37.0%),as for projects which didn't have professional standards(including TC,TG,UA and GLU),the main sources were manufacturer instructions of reagents/instrument(>41.1%)and National Clinical Laboratory Procedures(>45.3%).Moreover,more than half of laboratories(50.9%~58.9%)had verified the reference intervals.There were little difference among laboratories in the upper and lower limits of Cl,Ca,P,K and GLU,but bigger difference for other projects. Conclusion The upper and lower limits of reference intervals werenot consistent among laboratories.In order to ensure the comparability of the test results in beijing-tianjin-hebei region,laboratories should use reference intervals based on the popu-lation of beijing-tianjin-hebei region or China.