Valerian is a medicinal agent deriving from the plant Valeriana officinalis L. We reviewed the available literature on the use of valerian preparations in the treatment of neuropsychiatric disorders. Preclinical studies suggest that valerian has sedative and muscle-relaxant effects. Few clinical trials with valerian have been carried out in conditions other than insomnia. The insomnia studies have methodologic shortcomings but suggest that some preparations lead to significant subjective improvement in sleep complaints with remarkably few side effects. Furthermore, some evidence indicates that valerian preparations may have a mechanism of action and clinical characteristics that differ from the benzodiazepine-related sedative/hypnotics, making them more suitable for long-term use. If this safety profile and the plant's sedative/hypnotic efficacy are confirmed in double-blind, placebo-controlled trials with carefully and consistently prepared valerian compounds, then those compounds would fill an important and presently unfilled niche in the treatment of insomnia.