OBJECTIVE: to establish whether changes in a spoken verbal task performance while walking compared with being at rest could predict falls among older adults. DESIGN: prospective cohort study of 12 months' duration. SETTING: twenty-seven senior housing facilities. Participants: sample of 187 subjects aged 75-100 (mean age 84.8 +/- 5.2). During enrollment, participants were asked to count aloud backward from 50, both at rest and while walking and were divided into two groups according to their counting performance. Information on incident falls during the follow-up year was monthly collected. MEASUREMENTS: the number of enumerated figures while sitting on a chair and while walking, and the first fall that occurred during the follow up year. RESULTS: the number of enumerated figures under dual-task as compared to single task increased among 31.5% of the tested subjects (n = 59) and was associated with lower scores in MMSE (P = 0.034), and higher scores in Geriatric Depression Scale (P = 0.007) and Timed Up & Go (P = 0.005). During the 12 months follow-up, 54 subjects (28.9%) fell. After adjusting for these variables, the increase in counting performance was significantly associated with falls (adjusted OR = 53.3, P < 0.0001). Kaplan-Meier distributions of falls differed significantly between subjects who either increased or decreased their counting performance (P < 0.0001). CONCLUSIONS: faster counting while walking was strongly associated with falls, suggesting that better performance in an additional verbal counting task while walking might represent a new way to predict falls among older adults.