At present the dominant position among anti-anxiety medications has changed from meprobamate to the benzodiazepine derivatives. In order to avoid benzodiazepine's (BZ) undesirable side effects such as impairment of psycho-motor function, memory impairment, low dose dependence and withdrawal symptoms, a third generation anxiolytic agent, buspirone, the focus of the aryl-piperazine group of anti-anxiety agents, has been introduced recently. Aryl-piperazine derivatives work as 5-HT1A receptor partial agonists and are known as serotonin normalizers. Therefore, they are expected to have not only an anxiolytic function but also an anti-depressant effect as well. A characteristic of the aryl-piperazine derivatives is that they have no sedative and muscle relaxant effects, and they do not have BZ's undesirable side-effects, especially in regard to withdrawal symptoms. However they have a rather weak anxiolytic action and a slow onset of action. Aryl-piperazine derivatives will not take the place of BZ, but the use of BZ and buspirone as bridge medications, making the most of the strong points of both, can be proposed as a way to compensate for their respective clisadvantages.