Environmental laboratories could use a quality management system (QMS) to organize their management activities in order to promote the standardization and reliability of the results generated. This research aimed to construct and apply a diagnostic model to identify the implementation of the best quality management practices based on the ISO 17025 standard in an environmental
laboratory at the State University of Maringá, Brazil. The implementation of management practices was conducted over a period of ten months and two internal audits were performed using the developed model. The results of this study showed that the laboratory initially had 22.7% of compliance with the standard requirements and, after the corrective actions implemented, the system achieved 76.0% of compliance. Therefore, the practices adopted were important to solve problems encountered and to elaborate proposals for improvement actions for the consolidation of a QMS. The development of this work emphasizes the importance of organizational culture and employee training for the evolution of the QMS.