Because differential diagnosis between Parkinson's disease (PD) and multiple system atrophy (MSA) may be difficult due to overlapping of clinical features, especially at the early stage of the diseases, a search for additional clinical and instrumental markers increasing reliability of etiological diagnosis appears actual. The article presents the results of comprehensive comparison of parkinsonian signs and spectral electromyography (sEMG) data in 18 patients with MSA, diagnosed clinically according to criteria of Gilman et al (1998), and in 21 PD patients. Though no between-group differences in total expression of parkinsonian signs evaluated with The Unified Parkinson's Disease Rating Scale, part III, were found, MSA patients demonstrated progressive motor deficits, severer hypokinesia in the distal regions of the extremities, more pronounced impairment of axial movements, postural instability and gait disturbances but milder resting tremor, as compared to the PD patients (p < 0.05). Besides, the MSA patients were more frequently resistant to levodopa and had axial drug-induced dyskinesia (p < 0.05). An analysis of sEMG data revealed that MSA patients had a more prominent peak in 10-17 Hz frequency band (for arm muscles) and in Hz 7-14 (for leg muscles) as well as higher amplitudes peak frequencies (p < 0.05) positively correlated to hypokinesia severity. The results may be useful for differential diagnosis between PD and MSA.