This chapter reviews magnetic resonance spectroscopy (MRS) studies that were used to investigate neurochemical alterations in Parkinson's disease (PD). MRS has been demonstrated in vivo for different nuclei, including 1H, 31P, 13C, 15N, 19F, and 23Na. However, clinical applications are mostly limited to 1H and 31P isotopes. The chapter focuses on the use of 1H and 31P nuclei for MRS. 1H MRS allows detection of a variety of metabolites, including N-acetylaspartate (NAA) as a marker of neuronal loss/dysfunction, creatine (Cr) as a marker for deficits in energy metabolism, choline (Cho) as a marker for cell membrane turnover, and glutamate (Glu) and γ-aminobutyric acid (GABA), the primary excitatory and inhibitory neurotransmitters, respectively. 31P MRS evaluates high-energy phosphate compounds (HEPs), which reflect intracellular energy metabolism, such as adenosine triphosphate (ATP), phosphocreatine (PCr), and inorganic phosphate (Pi). The chapter also reviews clinically relevant and MRS-detectable metabolites, and illustrates potential applications in PD.