The in situ arterially perfused rodent preparation is an innovation that has allowed for significant progress in the study of cardiorespiratory reflex circuitry. This preparation provides a number of advantages over other preparations. The retention of peripheral cardiorespiratory afferents enables the study of reflex circuitry that is not possible in in vitro slice preparations. In addition, the in situ arterially perfused preparation provides unsurpassed mechanical stability of the brainstem compared with the in vivo preparation. This stability allows for better cellular recordings for prolonged periods. Here, the basic technique for the in situ arterially perfused preparation including recording of a number of cardiovascular and respiratory parameters is described. In addition, some of the common techniques for stimulating peripheral afferent nerves that produce different cardiovascular and respiratory reflex responses are discussed.