This study compares the characteristics of 492 patients discharged against medical advice from the Istituto Dermopatico dell'Immacolata, a Research Hospital (335 beds) in Rome specialized in Dermatology, Vascular Surgery and Plastic Surgery between 1995 and 1998, with those of 43,110 control patients discharged with physicians' approval according to a case-control model. In the multivariate analysis, male gender (OR 1.65; 95% CI 1.37-1.98) and residence in Rome area (OR 1.22; 95% CI 1.02-1.47) increased the odds of discharge against medical advice. The odds of such discharge decreased with increasing age (OR 0.994 per year; 95% CI 0.990-0.999). The proportion of patients discharged against medical advice decreased from 1.4% in 1995 to 0.4% in 1998. The average length of stay decreased from 1995 to 1998, with the exception of the Plastic Surgery unit. A retrospective review of the charts of 45 patients discharged against medical advice (AMA) within 48 hours from admission ascertained some of the stated reasons for discharge. Personal and family problems or refusal of treatment were reported for 35% of the patients. Of the 25 patients who gave no reasons, 11 asked again for hospitalization and 5 of these were rehospitalized by IDI within 10 days. This study also identified that the information on the medical record of patients who left against medical advice was generally poor. A standardized form for AMA discharges, including patient's understanding of the diagnosis, treatment, alternative therapies, consequences of refusing treatment and stated reasons for leaving against medical advice, might be of benefit to patients, physicians and hospital managers.