**Abstract**

The analyses performed in clinical laboratories require a high level of precision, selectivity, and sensitivity. The rising number of therapeutic agents from both the field of small and large molecules and the increasing use of modern screening approaches have brought mass spectrometry into almost every clinical laboratory. The need to screen the patients and to follow the therapy's success can often be fulfilled only by the highly selective and sensitive targeted approach with mass spectrometry. With improving instrument design and miniaturization of the separation technologies, mass spectrometry is no longer an exotic analytical approach. The use of mass spectrometry is now not restricted to the use in a clinical laboratory, but it is used in operating rooms for instant and on-site helping the surgeons with defining the margin of the tissue to be extracted. In this manuscript, we describe the use of mass spectrometry for selected clinical applications and show the possible way of future applications.

**Keywords:** Clinical laboratory, antibiotics, newborn screening, mass spectrometry
