The aim of this study is to determine whether the balance problems experienced by Parkinson’s disease (PD) patients may in part be due to dysfunctional processing of vestibular information, and to search for factors that may help predict the risk of falls. We evaluated the balance of 45 idiopathic PD patients and 20 healthy subjects by means of computerized dynamic posturography using sensory organization tests (SOT), rhythmic weight shift (RWS) tests and limits of stability (LOS) tests; and by the timed up-and-go (TUG) test. PD patients had poorer scores in the SOT than controls for overall balance and vestibular and visual inputs. They also performed worse in RWS and LOS tests, and were slower in performing the TUG test. Hoehn-Yahr stage did not correlate with vestibular input. Balance impairment in PD patients involves deteriorated processing of vestibular input, but this deterioration is independent of disease progression. Falls are related to PD patients’ reduced limits of stability.