In order to promote in Poland the effective response to the international food regulations and to enhance the ability of laboratories in proving their analytical quality assurance, some general guidelines for proficiency testing have been presented according to the internationally recognised protocol (IUPAC/ISO/AOAC The International Harmonized Protocol for Proficiency Testing). The objectives of proficiency testing and its importance for accreditation for analytical laboratories were also reviewed with the special emphasis given to those dealing with food analysis. The organization of interlaboratory trials and methods for statistical treatment of results were also described, as well as reporting of results and their statistical evaluation. The proficiency testing according to the above described rules are routinely performed by the Department of Environmental Toxicology of the National Institute of Hygiene for organochlorine pesticides and PCBs in food.