To assess the risk of hip fracture associated with the use of four classes of psychotropic drugs, we performed a case-control study of 1021 patients with hip fractures and 5606 controls among elderly Medicaid enrollees. Persons treated with hypnotics-anxiolytics having short (less than or equal to 24 hours) elimination half-lives had no increased risk of hip fracture. By contrast, a significantly increased risk was associated with current use of hypnotics-anxiolytics having long (greater than 24 hours) elimination half-lives (odds ratio, 1.8; 95 percent confidence interval, 1.3 to 2.4), tricyclic antidepressants (odds ratio, 1.9; 95 percent confidence interval, 1.3 to 2.8), and antipsychotics (odds ratio, 2.0; 95 percent confidence interval, 1.6 to 2.6). The risk increased in relation to the doses of drugs in these three classes. An analysis for possible confounding by dementia did not alter the results. Previous but noncurrent use of drugs in these classes conferred no increase in risk. Although a cause-and-effect relation was not proved, these data support the hypothesis that the sedative and autonomic effects of psychotropic drugs increase the risk of falling and fractures in elderly persons. The results suggest the need for studies of this association in other populations and for evaluation of newer psychotropic drugs with fewer undesirable sedative and autonomic effects.