The goal of the clinical laboratory is to produce analytical results that are free of errors and useful in the diagnoses of patients' conditions and in the treatment of patients. Every laboratory assay contains a certain amount of errors. This can be due to random error, which is unpredictable, or to systematic error, which is the result of the difference between the control analysis and the expected target value. The purpose of a good quality assurance-quality control program is to detect errors when they become clinically significant and to ensure that all laboratory procedures, including analytical procedures, are designed to deliver as good a test result as possible. Reproductive biology laboratories that deal in human in vitro fertilization or andrology will have to develop quality assurance-quality control programs, much like those of anatomical pathology laboratories, due to the unique type of services that they offer.