Around 20 to 50 million people are injured as a result of a road traffic accident (RTA) each year throughout the world. In the United Kingdom there have been considerable efforts made to review the assessment of whiplash claimants following RTAs due to the perceived level of fraud. However, very little has been done with regards to assessments for mental disorder; this article seeks to investigate how such assessments are undertaken. Data originating from one clinical forensic psychologist's practice ( = 305) are examined to provide an insight into the assessment of mental disorder in the medico-legal arena in the United Kingdom, building upon previous research. Many important findings emerged from this analysis including a complicated relationship between the diagnosis of mental disorder and the gender of the claimant. In addition, this article provides detailed normative data using the Symptom Checklist 90 Revised, the Impact of Events Scale, and the Beck Depression Inventory.