The importance of quality control for dramatically growing genetic tests continues to be emphasized with increasing clinical demands. Diagnostic genetics subcommitee of KSQACP performed two proficiency trials for cytogenetic study and one proficiency trial for molecular genetic tests in 2001. Cytogenetic surveys were performed by 32 laboratories and answered correctly in most laboratories except some problems in nomenclature and analysis for unbalanced whole arm translocation. Interpretation of special stain findings and fluorescent in situ hybridization (FISH) results has some problems to be improved. The proficiency trial for molecular genetic tests were molecular tests for genetic disorders including Huntington's disease(HD) and Leber Hereditary Optic Neuropathy(LHON), ABO genotyping, hematologic malignancies and infectious diseases including tuberculosis and hepatitis C. The trial materials for molecular tests were distributed to 52 laboratories and most of them revealed acceptable result except only small number of laboratories in HCV PCR. External quality assessment program for diagnostic genetics could be helpful to give participants many chances of continuous education and of interesting case materials.