This study was conducted to determine the prevalence of drug-related hospital admissions in southern Tasmania, Australia. The causes of consecutive admissions to medical wards of the Royal Hobart Hospital were reviewed. Comprehensive data were collected over a 10-week period on 691 admissions (median age: 67 years and range: 11-97 years; 50.8% males). Sixty-eight (9.8%) of the admissions were classified as being either probably or definitely drug-related. Most of these admissions were attributable to intentional overdose (38.2%) or an adverse drug reaction (30.9%). The overdoses often involved benzodiazepines or antipsychotics. Gastrointestinal bleeding related to the use of nonsteroidal anti-inflammatory drugs was the most common adverse drug reaction (38.1% of all reactions). Other drug-related admission categories were poor compliance (14.7%), dosage decrease or therapy cessation by a doctor producing an exacerbation of symptoms (7.4%), substance abuse (4.4%) and drug interaction (4.4%). Patients with a drug-related admission were, on average, younger than the other medical admissions, with no significant difference in gender. Patients admitted due to an overdose or substance abuse were younger than other drug-related admissions and non-drug related admissions. In conclusion, this study has determined that almost 10% of medical admissions to the hospital are drug-related and it is estimated that 40 to 50 elderly people are admitted each year suffering from gastrointestinal bleeding related to nonsteroidal anti-inflammatory drugs.