The term Lewy body diseases (LBDs) refers to a subset of neurodegenerative disorders that share the accumulation of the so-called Lewy bodies (LB) including: Parkinson’s disease (PD), dementia with Lewy bodies (DLB), and PD later characterized by the occurrence of dementia (PDD). Moreover, multiple system atrophy (MSA) and idiopatic Rem Sleeping behaviour disorders (RBD) complete the group of synucleinopathies and have also common symptoms with respect to LBDs. The clinical diagnosis of LBDs can be challenging for physicians, particularly in the early stages of disease. Given the growing number of individuals affected by these neurodegenerative disorders, early and accurate diagnosis can lead to improved clinical management of patients. For this reason, information obtained from molecular imaging biomarkers is playing an increasingly important role in this framework. The present narrative review discusses both established milestones and new evidence on the use of molecular imaging tracers already part of the clinical practice as well as available evidence on new molecular imaging approaches in PD, PDD and DLB.