Objective The purpose of this study is to investigate the effect of leg muscles activation on postural control in Parkinson’s disease (PD) patients with and without orthostatic hypotension (OH), and healthy controls. Methods Simultaneous center of pressure (COP), and electromyogram (EMG) of the bilateral tibialis anterior (TA), lateral and medial gastrocnemius (LG, MG), and soleus (SO) were recorded from 9 PD patients with OH (PD + OH), 12 PD patients without OH (PD – OH) and 12 healthy controls (HC) in supine (5 minutes), head-up tilt test (15 minutes), and standing positions (5 minutes). Convergent Cross Mapping (CCM) was used to examine the causal relationship between the individual leg muscles activity and postural control in the medial-lateral (ML), and anterior-posterior (AP) directions during standing. Results Preliminary results showed that PD + OH experienced higher postural sway in both ML and AP directions compared to HC and PD – OH, while no difference in postural sway was observed between PD – OH, and HC. Moreover, calf muscles (MG, LG, SO) showed a higher drive toward postural control in the AP direction in PD + OH compared to HC, while postural control through TA muscle was not different between PD + OH, PD – OH, and HC. Conclusions Our data suggests that PD patients with OH displayed higher postural sway which was accompanied with a greater drive of calf muscles toward postural control in the AP direction. The obtained results also suggest that calf muscles are mainly used to maintain balance in the AP direction. The findings of this study can assist in the development of an effective system for monitoring orthostatic intolerance via causal relationship between lower limb muscles activation and postural control to prevent syncope and falls.