Proficiency tests (PT) are essential for reliability and accuracy of analytical methods in Swiss milk laboratories. The project is dedicated to the organization and evaluation of PTs for testing key parameters in raw milk, such as salt concentration, fat content, dry matter, freezing point, somatic cell count, and bacteriological tests. A major goal is the harmonization of laboratory practices and validation of analytical methods to ensure compliance with quality standards. Participating laboratories analyze standardized samples under controlled conditions, which are statistically evaluated in accordance with ISO 5725 and ISO 13528. The results show that PTs contribute significantly to the consistency of results between laboratories. This strengthens consumer confidence, secures Switzerland's reputation as a country of excellence in milk production, and contributes to the production of high-quality dairy products. By promoting standardization and continuous improvement the high standards of the Swiss dairy industry are maintained ensuring that producers meet legal requirements and consumer expectations, thus securing international competitiveness.