PURPOSE: The aims of this study were to: 1) determine the concurrent validity of the mini-Balance Evaluations Systems Test (BESTest) and the instrumented test of postural sway (iSWAY) to quantify sensory orientation impairments in adults with known postural control deficits; and 2) determine the predictive validity of iSWAY to differentiate between fallers and non-fallers in adults with known postural control deficits. The Sensory Organization Test (SOT) served as the gold standard measure. METHODS: An exploratory methodological design using secondary analysis was used. The sample consisted of 45 subjects with Parkinson¡¦s disease (PD). Subjects were concurrently tested on SOT, mini-BEST, and iSWAY. DATA ANALYSIS: Frequency distributions, central tendencies, variability, and outliers were used to analyze goodness-of-fit to the normal distribution. Mean was used for age while mode was used for fall group, fall status, and gender. The following statistical tests were used: 1) Spearman rank correlation (rs) to measure the relationship between the the mini-BEST and SOT outcome scores; 2) parametric Pearson product-moment correlation (r) was used to measure the relationship between the iSWAY and SOT outcome scores; and 3) multiple regression to analyze the association between several independent variables (iSWAY scores) and dependent variable (number falls). A receiving operator curve was constructed to determine the iSWAY score that best discriminates fallers from non-fallers. RESULTS: There was a significant and fair correlation between mini-BESTest and SOT: Composite and Total rs = 0.380 (p = 0.010); Composite and Sensory rs = 0.343 (p = 0.021), Individual Items Eyes Open, Foam Surface (EOF) and Condition five rs = 0.399 (p = 0.007). There was insignificant and little-to-no relationship between mini-BESTest and SOT Condition one. There was a moderate-to-good inverse correlation between iSWAY and SOT: Composite r = - 0.634 (p = f¬0.01); Individual items ECF and Condition five r = -0.543 (p = f¬0.01). There was significant and fair inverse correlation between iSWAY and SOT Condition one r = -0.432 (p = 0.028). There was a predictive relationship between iSWAY RANGE Composite (p = 0.040) and RMS Composite (p = 0.021) and history of falls. A multiple regression equation including three iSWAY Composite scores explained 38% variability in reported falls. The ROC curve identified an iSWAY RMS Score of less than 0.249 as demonstrating the highest likelihood of differentiating between fallers and non-fallers. DISCUSSION: Mini-BESTest and iSWAY are clinically meaningful measures of sensory orientation in persons with PD. iSWAY can help better quantify sensory orientation impairments and inform other examination findings about history of falls. Future research is needed to investigate validity of these tests with other populations and expand validation of other test components.