Traditional treatment cultures, which have continued from ancient times to today and are preferred by 80% of the world’s population, include herbal therapy cultures created from various plants’ fruits, seeds, flowers, leaves, branches, or roots. The herbal medicines defined centuries ago may vary from person to person, and the cures obtained as a result of pioneering experimental applications by mixing different herbal products in different proportions have laid the foundation of treatment protocols developed in the modern world. These treatments, seen as complementary and supportive treatments in addition to pharmacological treatments, have been accepted by the World Health Organization and have taken their place in phytomedicine. Phytomedicinal (herbal) compounds are associated with a large number of biological reactions through various neurocognitive and neuropsychiatric interactions. It is known that they have essential effects on neuroendocrinergic system modulation, neuroprotection, regulation of mitochondrial energy pathways, cellular repair, and neurogenesis by stimulating and inhibiting central nervous system (CNS) activities through different pathways such as synthesis of neurotransmitters, enzymatic metabolism, interaction with other neurotransmitters and receptors. This chapter will explain the importance of phytomedicine in traditional and complementary medicine, and its neurocognitive effects on the mental system will be discussed.