Primary care providers are faced with numerous challenges when prescribing drugs for elderly patients. Multiple drug use, coexisting Illness, and normal physiologic changes associated with aging place older persons at increased risk for adverse drug reactions (ADRs). Sample selection bias in drug clinical trials and inappropriate prescribing of contraindicated drugs contribute to the risk profile. Because multiple drug use and ADRs are relatively common in the elderly, special caution should be used when prescribing for this population. The primary care provider should have a good understanding of the factors that put the elderly at increased risk for ADR, the classes of drugs inappropriate for elderly patients, the physiologic changes of aging that may produce an altered pharmacologic response, and the issues associated with adherence to drug therapy. This article Identifies factors that contribute to ADRs In the elderly and proposes strategies to reduce or avoid risk. Identifying and preventing ADRs in older Americans is a Healthy People 2000 health protection goal, perhaps more important given projected demographics over the next 20 to 30 years.