To assess the rate of occurrence of drug-induced illness as a cause for admission to the general medicine service of a community hospital, charts were reviewed retrospectively of all patients admitted to the service over two randomly selected one-month periods. Statistical analysis was performed on patients over and under the age of 65, and on iatrogenic and noniatrogenic admissions. Twenty-three of 244 patients (9.4%) were admitted with drug-induced illness. Patients with drug-induced illness had 5.7 medications as compared to 3.2 medications per patient admitted for other reasons (P less than .05). A single drug was responsible for 61% of all drug-induced illness admissions. Aspirin and other nonsteroidal anti-inflammatory agents were most often implicated. Eighteen of 155 elderly patients (11.7%) were admitted with drug-induced illness. These patients were on an average of 6.3 medications as compared with 3.8 medications per elderly patient admitted for other causes (P less than .005). Polypharmacy and a preponderantly elderly population may explain the substantial number of admissions caused by adverse drug reactions. Further research to assess the role of patient age and the number and type of medications involved in the event of drug-induced illness requires standardization of definition and diagnostic criteria.