A B S T R A C T Aims: To evaluate the performance of internal quality control in a biochemistry laboratory using Sigma metrics. Settings and Design: Data were extracted from December 2018 to November 2019 from a Tertiary care hospital, Coimbatore. Materials and Methods: The data regarding internal quality control (IQC) and external quality assurance scheme (EQAS) were collected for 14 biochemical parameters. Sigma metrics were calculated using total allowable error (TEa), Coefficient of

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... (CV) and percent bias for the above mentioned parameters. Quality goal index (QGI) ratio was used to analyze the reason for the lower sigma in analytes. Statistical analysis used: Coefficient of variance (CV) from the calculated laboratory means and calculated standard deviation. Sigma metrics was calculated from CV%, TEa and Bias. Quality goal index ratio was calculated from CV% and Bias. Results: In this study four parameters AST, ALP, Triglycerides and Amylase with sigma values >6; Six parameters Total Protein, ALT, HDL, Glucose, Calcium and Cholesterol with sigma values 3 to 6 and four parameters Albumin, Uric acid, Creatinine, and Urea with sigma values <3. For all analytes <6 sigma level, the quality goal index (QGI) was <0.8 indicating the parameters which needed improvement in imprecision, except for total protein and cholesterol whose QGI >1.2 indicated inaccuracy. Conclusions: In the present study Sigma value was highest for ALP (7.81) and lowest for Urea (1.27). Use of alternative methods can be done for the parameters whose sigma values less than 3 to improve their performance are recommended.