Objective: This review will indicate the quality of the evidence supporting the clinical effects of a number of commonly used types of herbal medicines for psychiatric and neurological disorders. Method: We conducted a review of literature to understand the biochemical and evidential bases for the use of herbs in psychiatric and neurological disorders as follow: 1) Alzheimer’s disease, 2) Depression, 3) Anxiety, 4) Insomnia, 5) Substance use disorders, 6) Attention deficit/hyperactivity disorder (ADHD), 7) Migraine. Results: Evidences support use of Ginkgo biloba, Huperzine A, Galantamine, Melissa officinalis,and Salvia officinalis for Alzheimer’s disease; St. John’s wort, Lavender, and Saffron for depression; Passionflower, and Kava, for anxiety disorders; Valerian, and English Lavender for sleep disorders; Hypericum for substance related disorders; Ginkgo biloba, and Passionflower for ADHD; and feverfew, and Butterbur root for migraine. The highest level of confidence derives from well-designed, randomized, double blind controlled studies. Conclusion: Herbs may have beneficial effects in variety of psychiatric and neurological disorder; however we must consider their potential side effects and drug-drug interactions.