Little is known about the pattern of psychiatric morbidity in arsonists referred for psychiatric evaluation, and how this compares with other violent offenders. Furthermore, there is uncertainty around whether there are differences in the psychiatric morbidity of female and male arsonists. We investigated all arsonists referred for an inpatient forensic psychiatric examination in Sweden over a five-year period (1997–2001). Diagnostic information was collected on 214 arsonists, of whom 155 were men and 59 women. Principal and comorbid DSM-IV psychiatric diagnoses in these arsonists were compared with those of 2395 other violent offenders who received forensic psychiatric examinations over the same period. We found the most common Axis I diagnoses for individuals convicted of arson and referred for forensic psychiatric evaluation were psychotic illnesses and substance use disorders. Compared with other violent offenders referred for forensic psychiatric examinations, arsonists were more likely to be diagnosed with a learning disability and, in the men, Asperger's syndrome. The pattern of psychiatric morbidity in these arsonists did not appear to differ between women and men. We conclude that the treatment needs of arsonists with psychiatric morbidity primarily relate to psychotic illnesses and substance use disorders. In addition, forensic psychiatric services could consider the involvement of learning disability expertise in meeting treatment needs.