The prevention of fall-related injuries in patients with Alzheimer-type dementia (ATD) is hampered by an incomplete understanding of their causes. We studied falls and fractures in 157 ATD patients, including 117 with three-year follow-up. Initially all but one patient could walk; 31% reported falls. During follow-up, 50% either fell or became unable to walk. The fracture rate during follow-up (69/1000/y) was more than three times the age- and sex-adjusted fracture rate in the general population. Features of both ATD and comorbid conditions contributed to the risk of falls and fractures. In particular, patients who experienced toxic reactions to drugs on entry into the study were more likely to report they had fallen prior to entry (odds ratio, 4.9; 95% confidence interval, 1.78 to 13.3), and patients who wandered were more likely to sustain fractures (odds ratio, 3.6; 95% confidence interval, 1.25 to 10.4) during the follow-up period, including hip fractures for which the odds ratio of 6.9 (95% confidence interval, 1.66 to 28.6) was unexpectedly high. Preventive measures may be possible, including controlling wandering, avoiding toxic reactions to drugs, and treating comorbid illnesses.