This chapter presents the practical aspects of selected microsurgical techniques that have numerous applications for studying the dynamics of neuro-endocrine interactions in the living animal. Although some of these techniques require specialized tools and fine surgical skills, they are not beyond the reach of many laboratories. Given that the demonstration of hormonal effects on in vitro systems always requires confirmation in vivo, it is likely that these microsurgical methods will continue to serve as indispensable tools for probing a variety of systems in the hypothalamopituitary complex. Although microsurgical techniques have been developed for a number of species, this chapter focuses on the rat, which has been used extensively for investigating neuro-endocrine mechanisms. It discusses microsurgical methods that have been adapted for use in unanesthetized, freely moving rats. These include posterior pituitary lobectomy (LOBEX), hypophysectomy (HYPOX), pituitary stalk section, and neural transplantation.