The purpose of this work was to investigate whether differences in length of hospitalization exist between burn patients with and without psychiatric comorbidity and, if so, why. The method undertaken was a retrospective file study from 1981 to 1995. Psychiatric patients with accidental burns are hospitalized longer than nonpsychiatric patients. However, psychiatric patients with self-inflicted burns are not hospitalized longer (after correction for the size of burn). The most likely reason for this is an excess of substance-dependent patients in the group of psychiatric patients with accidental burns. The often reported longer hospitalization of psychiatric patients may be restricted to substance-dependent patients and may be mediated by poorer physical condition.