The diagnosis of parkinsonism is essentially made by the presence of typical features including bradykinesia, plastic rigidity and resting tremor. However, in older persons, where the prevalence of parkinsonism is higher, the diagnosis is often inaccurate. The utilization of new radiological techniques, such as the DaT-SCAN SPECT, can improve the early diagnosis and treatment of these patients. However, no data are available at this moment in older population. Aims of this study were to investigate the role of the DaT-SCAN SPECT in the diagnosis of parkinsonism in older persons, and to propose a new diagnostic algorithm on DaT-SCAN SPECT to be used in older persons with parkinsonism. Patients evaluated at the Nuclear Medicine Unit of the University Hospital of Parma for diagnosis of parkinsonism from January 2009 to June 2012 who underwent clinical evaluation, and radiological assessment with DaT-SCAN SPECT, brain CT and MRI. A total of 267 patients, 147 men (55.06%) and 120 women(44.94%) with a mean age of 73.12 ± 5.08 years were enrolled in the study. In the multivariate linear regression analysis including age, sex, and bradykinesia, the presence of cerebral vascular lesions in the CT or MRI was the most significant predictive factor of abnormal DaT-SCAN SPECT uptake (beta± SE, p=0.002). The presence of bradykinesia remained also significantly associated with the DaT- SCAN SPECT uptake. In older subjects, the CT or MRI detection of cerebral vascular lesions and the presence of bradykinesia are the most significant predictors of abnormal DaT-SCANTM SPECT uptake. The timing of scan execution and the coexistence of motor and cognitive deficits, are key elements to improve the accuracy of early detection of altered nigrostriatal system, for avoiding misdiagnosis and side-effects of medications inappropriately started in older persons. This study could facilitate clinicians to treat older persons with Parkinson's disease and to ameliorate the accuracy of the diagnosis for testing the effects of new drugs affecting the natural history of this neurodegenerative disease. The accuracy of the diagnosis could permit an early identification of these diseases, and could permit to test neuroprotective drugs in early phase of patients with Parkinson's disease.