Abstract: Objective　To evaluate the performance of routine clinical chemistry items by the statistical method of total error（TE） and uncertainty.   Methods　The data of internal quality control were collected by Shanghai Centerfor Clinical Laboratory Internal Quality Control software，from January to September 2012，and the accumulation means（），accumulation standard deviations（s） and accumulation coefficients of variation（CV） were calculated. The relative bias（bias%） and relative average bias（bias%） of routine clinical chemistry item results and targetvalues were calculated according to the 2 reports of College of American Pathologists（CAP） external quality assessmentplans（C3-A and C3-B）. TE was calculated by the data of accumulation CV. By Nordtestmethod，the uncertainties of routine clinical chemistry items were calculated according to the external quality assessmentdata of CAP and internal quality control accumulation CV. Results　The routine clinical chemistry items included glucose（Glu），creatinine（Cr），urea nitrogen（BUN），total protein（TP），albumin（Alb），uric acid（UA），total bilirubin（TBil），alanine aminotransferase（ALT），cholesterol（Chol），triglyceride（TG），aspartate aminotransferase（AST），alkaline phosphatase（ALP），lactic dehydrogenase（LDH） and high-density lipoprotein cholesterol（HDL-C），and their maximum TEs with every 3 internal quality control levels were 5.40%，6.01%，9.37%，3.00%，6.52%，3.77%，26.79%，5.34%，4.03%，9.42%，9.25%，8.37%，6.19% and 9.54%. The uncertainties were 6.37%，6.50%，10.64%，3.23%，13.01%，4.84%，31.07%，6.00%，4.37%，13.27%，14.12%，10.07%，6.95% and 14.08%. The results of all items，exceptAlb，were within Clinical Laboratory ImprmeyentAmendment（CLIA′88） ranges and biological variation allowable ranges. Conclusions　Both TE and uncertainty have good consistency，and they can be the importantreferencefor the analysis and improvementof laboratory examination quality.

Key words: Total error, Uncertainty, Biological variation