Trade in animals and animal products has reached global proportions and so too has the threat of infectious diseases of veterinary importance. The Manual of Standards for Diagnostic Tests and Vaccines, published by the Office International des Epizooties (OIE), contains chapters on infectious diseases that may cause various degrees of socio-economic, public health, and/or zoo-sanitary consequence. These chapters cover the major diseases of cattle, sheep, goats, horses, pigs, poultry, lagomorphs and bees. A number of factors are considered when qualifying animals and animal products for international trade including epidemiological, clinical and testing parameters. Of particular note and relevance is a strong international movement to standardize the test methods and reference reagents in order to promote harmonization of testing and facilitation of trade. There is message here that is directed to those of us involved in the development and application of test methods for infectious disease diagnosis. Serological test methods have been and still remain the mainstay of diagnostic methods prescribed for trade. More than ever, there is a need to observe and apply international guidelines for the development and validation of serological test methods. There is also a need to develop international standard reagents for use in the calibration of test methods and the production of national and working standards. In the future, veterinary diagnostic testing laboratories involved in trade may also require a form of international accreditation unique to their specialty. This presentation describes the current developments in international standardization of test methods and reference reagents. (C) 1999 Elsevier Science B.V. All rights reserved.