OBJECTIVE: To investigate heart rate variability (HRV) in patients with Essential Tremor (ET) in comparison with patients with Parkinson\'s Disease (PD). METHODS: This is a cross sectional control study including 10 patients with ET, 10 patients with PD and 10 age-sex-matched controls. In patients and controls, we measured the components of HRV analysis in the frequency domain during a daytime period of 12-h. Selected HRV variables were low-frequency (LF) and high-frequency (HF), conventionally considered to be influenced by the sympathetic system and the parasympathetic system respectively. RESULTS: HRV variables, in patients with ET, were significantly different from those detected in PD patients and similar to those of controls while in PD patients, they were significantly different from those of controls. At cut off level of 654 ms(2), LF component correctly distinguished ET patients versus PD with sensitivity, specificity, PPV and accuracy of 100%. By contrast, at cut off level of 737 ms(2), HF component showed sensitivity, specificity, PPV and accuracy of 80%, 100%, 100%, and 86.67% respectively. DAT-SPECT and cardiac MIBG uptake were both normal in ET patients whereas they were markedly decreased in those with PD. CONCLUSIONS: In our study, the LF component of HRV analysis distinguishes ET patients from those with PD on an individual basis, thus representing a valid help in everyday clinical practice for differentiation between these patients in absence of scintigraphic investigations.