Participation in inter-laboratory comparison programs is an important means of laboratory quality control and assessing laboratory performance, and these programs can be used by customers or regulatory bodies for the selection of qualified laboratories. This research describes how to use inter-comparison tests and how to statistically analyse the test results. This research has a practical study of assessing laboratories performance in laboratories of the Syrian textile firms by distributing samples simultaneously to participating laboratories for testing. After collecting test results, the researcher used scientific methods to handle data to identify the weak points in laboratories performance and provide them the Feedback and technical advice to Assistance the lab to defining the measurement problems and evaluating of test methods and instrumentation , and could introduce some suggestions and recommendations to overcome.