Drugs of natural origin still play a major role in the treatment of many diseases and as lead structures for the development of new synthetic drug substances. This review article deals the pharmacological effects on the Central Nervous System (CNS) of some plant extracts and their isolated chemical components due to their monoamine oxidase (MAO) activity. Herbs and herbal preparations containing MAO-A inhibitors have been widely used as an effective alternative in the treatment of neuropsychiatric diseases such as depression. Inhibitors of MAO-B not only enhance dopaminergic neurotransmission but also prevent activation of toxin and free radical formation, alleviating the process of neuron denaturalization, on account of which they are used in Parkinson disease (PD). Several methods have been developed for monitoring MAO activity and its inhibitor screening of bioactive natural products.