Abstract Sympathetic innervation plays a crucial role in regulating blood flow, chronotropism, dromotropism, lusitropism, and myocardial inotropism. In several cardiac and neurodegenerative disorders, the autonomic nervous system (ANS) undergoes alterations. Cardiac neuronal imaging can aid in understanding the pathophysiology, diagnosis, and prognosis of these conditions. This article provides a clear and objective overview of the step-by-step procedure for mIBG-I123 scintigraphy, which assesses cardiac sympathetic activity in primary clinical practice settings.