Magnetic resonance spectroscopy is a noninvasive technique which allows the study of the chemical composition of tissue. In the first part of this paper the authors describe the physical principles and the technical features of spectroscopy, including spectral acquisition, localization techniques and peak quantification. The second part of the paper regards the evaluation of the biological significance of the peaks observed in the most frequently studied spectra (31P and 1H). The third part concerns the clinical feasibility of magnetic resonance spectroscopy: in order to employ spectroscopy in the clinical practice, this technique should be able to fulfill such requirements as tissue characterization, metabolic quantification, therapy follow-up, biochemical understanding of the physiopathologic phenomena and pH evaluation. The fourth and last part of this paper deals with the clinical applications of spectroscopy. The authors consider the results of other research groups in the spectroscopic evaluation of the striate muscle, the central nervous system, heart, liver and some other organs. Then they describe some preliminary personal results in cerebral spectroscopy (41 healthy subjects studied with 31P and 5 with 1H) and liver spectroscopy (19 healthy subjects studied with 31P and 9 healthy subjects and 9 patients with liver steatosis studied with 1H). The authors conclude that the problem of the potential clinical application of spectroscopy is still open. So far the use of this technique is limited to research centers, which should point out the clinical role of spectroscopy.