This Master s Degree dissertation addresses the development in adjustment and validation and the metrological reliability of laboratory services covering horseracing activities. The work includes (i) the specification of the performance of an antidoping laboratory capable of identifying the presence of forbidden substances, as defined by the horse-racing industry; (ii) the validation of analytical methods applicable in doping tests of biological matrices of competing animals to Brazilian laboratories conditions, and (iii) the definition of a standard of excellence in harmony with the criteria of the International Federation of Horseracing Authorities as the tools utilized for the accreditation of the antidoping laboratory and the subsequent participation in international agreements of mutual recognition. In order to validate the methodology, the Brazilian Jockey Club Antidoping Laboratory (LAD/JCB) was used as a studycase. Original in its scope, this work contributes towards the widening of the accreditation of laboratories in Brazil, considering the fact this new category of testing laboratories is still nonexistent within the Brazilian network of accredited testing laboratories which considers the international standard ISO/IEC 17025 as the basic criteria. With regard to development, some relevant aspects are still being discussed in relation to the laboratory management system: the unreliability of the measurements for the determination of doping, in view of internationally accepted practices and procedures; qualification of specialized technical personnel; traceability of SI (the International Unit System) and the validation and adjustment of analytical methodologies utilized in antidoping laboratories. Special attention is dedicated to Methode Alcalins Sur C- 18, developed by Laboratoire LAB-Contrôle Antidopage in France, applicable to the determination of the presence of doping substances in the biological matrix (urine) of racehorses, used as method source for the development of an alternative method adjusted to the Antidoping Laboratory of the Brazilian Jockey Club conditions and molded to detection of the more frequents doping substances in the brazilian horserancing activities. Having the caffeine been the doping substance statistically identified as the most frequent in the tests carried out by the Brazilian Jockey Club Antidoping Laboratory, along its seven years of services, the Methode Alcalins Sur C-18 was adapted and validated for its analytical determinations. The applied research carried out was also credited with the introduction of a new attribute to the methodology qualitative validation, designated as limit- value for determination, which provides key-information for the determination of a concentration band, in order that incorrect results (false-positive and false- negative) do not appear in the laboratory reports usually issued. Besides the adaptation and validation of the analytical method thus developed, this Master s Degree dissertation contributes not only towards greater visibility of a new category of laboratories, but mainly to the preparation of the Brazilian Jockey Club Antidoping Laboratory to demonstrate its technical capacity as a policy and strategy for becoming in the near future an internationally recognized accredited laboratory. The present M.Sc. Dissertation addresses the metrological reliability of antidoping laboratories, a pioneering issue in Brazil, aiming at the solution of a problem related to the horse-racing industry. It was developed under the financial support of the FINEP/MCT Agreement no. 22.01.0692.00, Reference 1974/01 (Green-Yellow governmental Sectoral Fund) which droved research cooperative efforts in metrology to the solution of ten pilot-projects. In this case specifically, cooperated to the development of the M.Sc. research entitled Metrological reliability of the Antidoping Laboratory of the Brazilian Jockey Club