Major depressive disorder (MDD) is a chronic mental disease affecting over 300 million people worldwide with limited treatment options. Understanding the neurochemical processes in MDD is essential for developing innovative medications, and magnetic resonance spectroscopy (1H MRS) is especially well-suited for its in vivo exploration. This chapter compares the consistent1H MRS evidence from the animal models to the clinical findings. The clinical results largely correspond to the animal studies in the prefrontal cortex, where the higher choline and lower Glx (glutamate + glutamine) levels are reported. These markers indicate cell membrane turnover and neuronal metabolism dysfunction. The hippocampus in MDD patients is understudied in the clinical field making an assessment of consistency of preclinical and clinical findings impossible. The use of1H MRS method provides new insights into neuro-molecular process in MDD and has a potential to become a useful biomarker for tracking the success of treatment interventions in MDD.