Functional Neuroimaging has been traditionally used in research of patients with different Parkinsonian syndromes. However, the emergence of commercial radiotracers and the availability of positron emission tomography (SPECT) and more recently of positron emission tomography (PET) have permitted their routine use in the clinical practice. Particularly, the development and degree of clinical evidence achieved by the functional neuroimaging techniques over the past two decades have resulted in the progressive inclusion of several biomarkers in the clinical diagnostic criteria of neurodegenerative diseases that occur with Parkinsonism. However, the diversity of radiotracers designed to assess the involvement of different pathways in the neurodegenerative process underlying Parkinsonian syndromes (dopaminergic nigrostriatal pathway integrity, basal ganglia and cortical neuronal activity, myocardial sympathetic innervation), and the different neuroimaging techniques available (scintigraphy, SPECT and PET) have generated some controversy concerning the best neuroimaging test that should be indicated for the differential diagnosis of Parkinsonism. In this article, a panel of nuclear medicine and neurology specialists has evaluated the functional neuroimaging techniques available placing special emphasis on practical considerations of the diagnosis of patients with Parkinsonism of uncertain origin and the assessment of the progression of Parkinson's disease.