Abstract: Objective To observe the maintenance and regular calibration of the semi-automatic biochemical analyzer in order to reduce blood discarding caused by ALT unqualified detections and reports. Methods Semi-automatic biochemical analyzer was calibrated every 3 months based on CLSI EP15-A guidelines. The tests were performed on one test per day for 5 days,2 concentrations per day and 3 repeats for each concentration of one sample. The additional analyses were performed and the data were eliminated in case that the quality was out of control. Results The frequencies of blood discarding due to unqualified ALT detections were gradually decreased to 5.15%（3 828/74 320）,2.14%（1 633/76 313）,2.22%（1 759/79 232）,1.57%（1 228/78 238）and 0.68%（574/84 406）（P<0.01）,respectively by a good maintenance and calibration of the instrument every three months. Conclusion The methods of nice maintenance and regular calibration of semi-automatic biochemical analyzer recommended by CLSI EP15-A may help reduce the blood discarding caused by ALT false detections and reports.

Key words: Blood station, Maintenance and calibration, ALT false detection