Physical, chemical, and biological measurements are important essentials in medical diagnosis for the prevention and treatment of disease as well as for risk assessment and monitoring of patients. Hence, measurement results that are relevant to medical diagnosis must be accurate, reliable, and comparable between different places and over time to ensure optimum patient care as well as the most efficient use of available health care funds. To ensure that medical measurement results are of known quality and to improve their accuracy and reliability, standards, reference methods, certified reference materials, and calibrations are needed. In this article, the peculiarities of medical measurements are discussed and problems encountered in fulfilling the above‐mentioned requirements are pointed out.