Microdialysis is a well-established sampling method for collecting neurotransmitters from the brains of freely moving rats (1 ; see also Chapter 19 ). To measure levels of amino acid transmitters in the microdialysates requires very sensitive methods of analysis owing to the subpicogram amounts of amino acids in small volumes of dialysates (in our experimental setup, the total volume is usually 40 �L). Often, conventional liquid chromatography (LC) systems are unable to provide the necessary sensitivity and, therefore, microbore LC has become a valuable analytical tool for the neurochemist (2 ,3 ). The general principles, advantages, and disadvantages of microbore LC as an analytical method for measuring neurotransmitter levels in microdialysates are discussed further in Chapter 14 . In this chapter, two different microbore LC methods—each optimized for analysis of different amino acid transmitters—will be described. Both methods are selective, robust, and can be automated.