OBJECTIVE: To examine the relationship of the Berg Balance Scale (BBS) to outcome after acquired brain injury. METHODS: Forty consecutive patients with acquired brain injury were admitted for multidisciplinary rehabilitation. Patients were assessed with the BBS. The BBS was originally designed as a quantitative measure of balance and risk for falls in community-dwelling elderly patients. The BBS comprises 14 different tasks graded on a 56-point scale. Community-dwelling elders with a BBS score of < or = 42 have > 90% risk for falls. RESULTS: In our study, there were 27 patients with a low BBS score (< or = 42) and 13 patients with a high BBS score (> or = 43). The discharge total Functional Independence Measure (FIM) scores were lower in the low BBS patients (96.4 +/- 21.2) compared with the high BBS patients (111.5 +/- 12.5) (p < 0.007). The length of stay (LOS) was significantly longer in the low BBS patients (38.9 +/- 18.5 days) compared with the high BBS patients (14.2 +/- 6.1 days; p < 0.000). Among the three patients that experienced falls during their hospitalization, all exhibited low BBS scores. The admission BBS score strongly correlated with admission total FIM scores (r = 0.86; p < 0.000) and moderately correlated with discharge total FIM scores (r = 0.56; p < 0.000) and LOS (r = -0.55; p < 0.000). Using a multiple regression analysis, the admission FIM score was found to be the better predictor of discharge FIM scores, and time admitted after injury was the better predictor of LOS. CONCLUSIONS: Prediction of rehabilitative outcome might be enhanced by the use of the BBS scores in combination with other clinical measures on admission to inpatient acute rehabilitation.