The accurate measurement of sympathetic nerve activity is essential for advancing knowledge related to the mechanisms that underpin sympathetic activation in diseased states, such as acute heart failure. Considering sympathetic outflow throughout the body is differentially modulated, the most reliable method of measuring sympathetic traffic to individual organs is by way of direct electrophysiological recording of nerve activity. However, the surgical approach of accessing, exposing, and isolating the sympathetic nerve of interest is technically demanding, especially in the small size of a standard laboratory rat, one of the most common models for measuring SNA. Moreover, preserving the health of the nerve while attaching it to electrodes for recording requires careful diligence. The complexity of recording from specifically the cardiac sympathetic nerve remains a significant challenge due to the difficulty of accessing the nerve within the thorax cavity. Here, we describe in detail the process of surgically isolating the cardiac sympathetic nerve activity in a rat for accurately recording and quantifying sympathetic nerve activity.