Polypharmacy, the inappropriate use of multiple drug regimens, has a significant impact on the health of elderly individuals. Drug use increases with age, but suitability of therapy is sometimes difficult to define. In ambulatory and hospital care, there is some documentation of poor prescribing practices by physicians and drug misuse by patients. Sound data suggest that polypharmacy and drug misuse are highly prevalent in long-term care facilities. Psychotherapeutic agents are the most commonly misused drugs by physicians in this setting. Polypharmacy is associated with factors such as the number and severity of illnesses, hospitalization, number of physicians seen, number of pharmacies used, and possibly increased patient age. Methods to prevent polypharmacy and drug misuse have not been well studied. There is a need for intensive research to define effective methods to strengthen prescribing practice of physicians for elderly patients, to promote cooperation among health care personnel in ensuring optimal drug use by patients, and to enhance the role of patients as responsible partners in drug therapy. The authors are confident, however, that drug misuse and polypharmacy can be reduced in older persons by the use of current knowledge of risk factors associated with polypharmacy and by improved communication between the physician and patient.