To assess internal consistency and validity of measures of balance (Berg balance scale, BBS), postural changes (postural changes scale, PCS) and fear of falling (fear of fall measure, FFM) in 70 ambulant Parkinson's disease (PD) persons, these instruments were matched with performance-based balance and mobility tests, and other clinical, functional and quality of life PD-specific measures. The BBS, PCS and FFM showed a good internal consistency, moderate to good inter-correlation, and a significant correlation with measures of both disability (UPDRS-ADL, Schwab and England scale) and--to a lesser extent--impairment/severity of symptoms (UPDRS-ME, Hoehn and Yahr Scale). Tandem Romberg, Single-Limb Stance, Functional Reach, and the Timed Up & Go test correlated slightly better with BBS than with PCS and FFM. This study shows that problems of balance and postural control in PD patients result from complex interactions between motor impairment, functional abilities and fear of falling.