Objectives: To investigate exercise effects on falls in people with dementia living in nursing homes, and whether effects were dependent on sex, dementia type, or improvement in balance. A further aim was to describe the occurrence of fall-related injuries. Design: A cluster-randomized controlled trial. Setting and Participants: The Umeå Dementia and Exercise study was set in 16 nursing homes in Umeå, Sweden and included 141 women and 45 men, a mean age of 85 years, and with a mean Mini-Mental State Examination score of 15. Intervention: Participants were randomized to the high-intensity functional exercise program or a seated attention control activity; each conducted 2-3 times per week for 4 months. Measures: Falls and fall-related injuries were followed for 12 months (after intervention completion) by blinded review of medical records. Injuries were classified according to severity. Results: During follow-up, 118 (67%) of the participants fell 473 times in total. At the interim 6-month follow-up, the incidence rate was 2.7 and 2.8 falls per person-year in exercise and control group, respectively, and at 12-month follow-up 3.0 and 3.2 falls per person-year, respectively. Negative binomial regression analyses indicated no difference in fall rate between groups at 6 or 12 months (incidence rate ratio 0.9, 95% confidence interval (CI) 0.5e1.7, P ¼ .838 and incidence rate ratio 0.9, 95% CI 0.5e1.6, P ¼ .782, respectively). No differences in exercise effects were found according to sex, dementia type, or improvement in balance. Participants in the exercise group were less likely to sustain moderate/serious fall-related injuries at 12-month follow-up (odds ratio 0.31, 95% CI 0.10e0.94, P ¼ .039). Conclusions/Implications: In older people with dementia living in nursing homes, a high-intensity functional exercise program alone did not prevent falls when compared with an attention control group. In high-risk populations, in which multimorbidity and polypharmacy are common, a multifactorial fallprevention approach may be required. Encouraging effects on fall-related injuries were observed, which merits future investigations.