PROFICIENCY TESTING IS DEFINED IN ISO/IEC 17043 AS THE EVALUATION OF PARTICIPANT PERFORMANCE AGAINST PRE-ESTABLISHED CRITERIA BY MEANS OF INTERLABORATORY COMPARISIONS. THUS, PROFICIENCY TESTING IS AN ESSENTIAL PART FOR MAINTAINING AND IMPROVING THE QUALITY IN MEDICAL LABORATORIES AND COMPLEMENTS THE INTERNAL QUALITY CONTROL RUN IN A LABORATORY TO MONITOR THE DAILY PERFORMANCE. THE SYNONYMOUSLY USED TERM EXTERNAL QUALITY ASSESSMENT (EQA) EMPHASIZES THE CONJUNCTION BETWEEN INTERNAL QUALITY CONTROL AND PROFICIENCY TESTING/EXTERNAL QUALITY ASSESSMENT...