Mass spectrometry is an analytic technique with high specificity and a growing presence in laboratory medicine. Various types of mass spectrometers are being used in an increasing number of clinical laboratories around the world, and, as a result, significant improvements in assay performance are occurring rapidly in areas such as toxicology, endocrinology, and biochemical genetics. This review serves as a basic introduction to mass spectrometry, its uses, and associated challenges in the clinical laboratory and ends with a brief discussion of newer methods with the greatest potential for clinical diagnostics.