OBJECTIVE: To establish an internal quality control method for the blood concentration of theophylline by enzyme-linked immunosorbent assay（ ELISA） using Westgard multiple rules theory. METHODS: 5. 0 μg/ml

10. 0 μg/ml and 20. 0 μg/ml of quality control serum of theophylline were prepared

after 20 consecutive working days of monitoring on low

medium and high concentration of quality control serum

Levey-Jennings quality control charts and Z-score quality control charts were plotted

and Westgard multiple rule was used for its quality assessment.RESULTS: The precision

stability and recovery test results of the low

medium and high concentration of quality control serum of theophylline were all in accordance with the requirements; both the Levey-Jennings method and Westgard multiple rule control method suggested no uncontrolled situations. CONCLUSIONS: Using the internal quality control assessment system to conduct evaluation on blood concentration monitoring data of theophylline can ensure the accuracy and reliability of blood concentration determination

thus providing accurate information for clinical rational drug administration.