This study was undertaken to identify the demographic characteristics of patients aged 55 or older in a drug-overdose group admitted to the Emergency Department of Arizona Health Sciences Center during the 3-year period, August 1975-July 1978. Of the 646 overdose patients observed, 60 (9.5 percent) were aged 55 or older; of these, 77 percent were women--a significantly higher proportion than in the rest of the overdose group. The majority of the overdose incidents were unintentional, and most patients required hospitalization. For the elderly, the drugs involved in the overdoses did not differ significantly from those ingested by others in the overdose group. Concurrent traumatic injury occurred more often in the older age group, necessitating a longer hospital stay and higher health care costs. Drug overdosage is a significant problem in the elderly population. Since many overdose are unintentional, elderly persons in particular require the counsel of physicians and pharmacists in the medication process.