The motor dysfunctions always affect hemi-body first in Parkinson's disease (PD). However, the interhemispheric relationships in patients with only unilateral motor impairment were barely known to date. In this study, 43 unilateral-symptomatic PD patients (UPD, Hoehn-Yahr staging scale, H-Y: 1-1.5), and 54 NC were recruited. We aimed to investigate the interhemispheric coordination and hemispheric dominance pattern for further understanding the pathogenesis of PD. We found that the disrupted interhemispheric coordination in bilateral sensorimotor regions may have significant implications for elucidating the mechanisms underlying the hemiparkinsonism and enabling the individual diagnosis and assessment of early PD.