The principles of good laboratory practice (GLP) can be considered as a code of general behaviour potentially applicable to all experimental studies, although they were first conceived for harmonizing the conduct and assessment of toxicological tests designed to evaluate the impact of chemical substances on human health and the environment. From a general standpoint, therefore, GLP criteria aim at generating credible, comparable and cost-effective experimental information that can in turn make the decision-making process easier and sounder. On the other hand, of equal importance at the global level is the availability of and access to the wealth of critically assessed, self-consistent chemical data thus produced. Under both respects a key role is played by the activities undertaken under the aegis of international bodies such as the Organisation for Economic Cooperation and Development (OECD), the Commission of the European Union (CEU) and the International Register of Potentially Toxic Chemicals of the United Nations Environment Programme (IRPTC-UNEP). This cultural and scientific humus has been incorporated into legal provisions by most industrial countries to regulate production and commercialization of chemical substances. As regards Italy, the act DLvo no. 120 of 27 January 1992 focuses on the adoption of GLP principles by national test facilities and covers all possible categories of chemicals, namely industrial substances, pharmaceuticals, cosmetics, pesticides, food additives and still others. Accordingly, the compliance status with GLP principles of a test facility is ascertained by inspections carried out by public officers following a detailed procedure which will eventually result in the above acknowledgement provided that no major deviations in the laboratory performance are detected.(ABSTRACT TRUNCATED AT 250 WORDS)