Signs or symptoms of impaired autonomic regulation of circulation are typically present in patients affected by Parkinson's disease (PD), in agreement with the cardiac sympathetic denervation discovered by Goldstein more than 15 yrs. ago. In particular, the majority of PD patients have a diffuse left ventricular myocardial sympathetic denervation, being a normal neurological condition present only in a small number of affected subjects. Actually MIBG cardiac imaging is a universally accepted method to estimate cardiac sympathetic innervations. This review covers the role of MIBG cardiac imaging in PD as well as in other parkinsonisms, focusing the attention on technical problems and pathophysiological premises for cardiac denervation. In particular new emerging data support the role of MIBG as biomarker of PD, also before motor symptoms became clinically evident. Therefore the timing of cardiac noradrenergic denervation in PD is a key issue and we want to update the analysis of autonomic cardiovascular abnormalities studied with MIBG in PD and related disorders.