External Quality Assessment Schemes (EQASs) give evidence about test performance and interpretation of results in routine and specialized laboratories as well as about quality and comparability of tests of different manufacturers. The EQASs organized for Germany, collaborating 17 countries and WHO (40 countries) revealed two main results: (i) The technical performance of most tests (PCR and immunology) was surprisingly good in the majority of participating laboratories. (ii) In some cases, however, unexpected test immanent problems became evident which could be eliminated after revision of the method. This improvement of test quality was based on 10 years experience with 370 EQASs with more than 750 participating laboratories testing 260,000 samples. These samples, well characterized by a broad spectrum of users (institutes of basic science, universities, hospitals, blood banks, governmental institutions and small private laboratories up to industries), have been proven as ideal material for national references, for development, evaluation and licensing of tests as well as for daily internal run controls.
