Monoamine oxidase inhibitors (MAOIs) were the first type of antidepressant developed. MAOIs elevate the levels of norepinephrine, serotonin, and dopamine by inhibiting an enzyme called monoamine oxidase. They are also used in the treatment of Parkinson's disease, tuberculosis, and several other disorders. Therefore, it is very important to develop efficient analytical methods for monitoring and management. There are two isoforms of monoamine oxidase, MAO-A and MAO-B. In this article, analyses of MAOIs in pharmaceutical formulations and biological fluids were reviewed from 2000 to the present, including all types of chromatographic, spectrophotometric, electrophoretic, and voltammetric techniques, focusing on isoniazid, tranylcypromine, moclobemide, rasagiline, and selegiline.