Abstract: Objective To improve HLA genotyping performance in clinical laboratory,the results of National Proficiency Testing（PT）for HLA-A/B/DRB1 low-resolution genotyping were collected and summarized from 2017 to 2020. Methods HLA genotyping results from 2017~2020 PT were analyzed and different kinds of errors were described and classified,and the possible reasons were also analyzed. Results The number of participant laboratories was increasing from 78 to 96 during 2017 and 2020. 12 096 HLA alleles were returned from the participants during the 4 years and total of 127 errors（1.05%）were found. These 127 errors were classified into two major types including 13 technical errors and 114 artificial errors. The proportion of laboratory which made mistakes was 2.56％（2/78）、4.88％（4/82）、8.75％（7/80） and 3.13％（3/96）in 2017,2018,2019 and 2020,respectively. Conclusion There were above 2.5% of laboratories with errors in HLA genotyping PT surveys past four years. More attentions should be greatly paid to clinical HLA genotyping test and the procedure of reporting.

Key words: Human leukocyte antigen （HLA）, Low-resolution genotyping, Proficiency Testing （PT）