Neuroimaging with single photon emission computed tomography (SPECT) and positron emission tomography (PET) involves the use of radiolabeled ligands for the in vivo evaluation of brain perfusion, metabolism, and neurotransmitter pathways. These techniques have been used for the in vivo assessment of the key neurochemical pathway that is involved in Parkinsonian disorders, i.e., the dopaminergic pathway. Evaluation of the cholinergic and serotonergic pathways that have also been implicated in Parkinson’s disease is less commonly performed in routine clinical practice. This chapter covers the neurotransmitter imaging in Parkinson’s disease, metabolic imaging with F-18 fluorodeoxyglucose in Parkinsonism, dopaminergic and metabolic functional neuroimaging markers used for diagnosis and differential diagnosis of Parkinsonism, and imaging cardiac sympathetic denervation in idiopathic Parkinson’s disease.