This chapter discusses the influence of benzodiazepine (BDZ) on the developing brain. In recent years, neural receptors mediating the pharmacological effects of many neuroactive drugs are identified. Of particular pertinence to this discussion, specific neural binding sites for the anxiolytic BDZ compounds are identified and the interaction of these drugs with their binding sites correlates well with their anxiolytic, anticonvulsant, sedative and muscle-relaxant properties. The full expression of drug interaction with neural receptors during development can also depend upon the neural interactions that receptive cells make with other neurons and upon the maturational state of specific neural circuitry. Developmental exposure to BDZs is associated with neural, physiological and behavioral alterations in both clinical and experimental studies. The scope of the discussion is limited to the presentation of results of research on the effects of in utero exposure to BDZs in rats. To understand the implications that binding of drug to specific sites in fetal brain, it is necessary to demonstrate a response in the fetal brain to the presence of the drug.