Background Patients with a severe mental illness (SMI) are more likely to experience victimisation than the general population. Aims To examine the prevalence of victimisation in people with SMI, and the relationship between symptoms, treatment facility and indices of substance use/misuse and perpetration, in comparison with the general population. Method Victimisation was assessed among both randomly selected patients with SMI (n = 216) and the general population (n=10 865). Results Compared with the general population, a high prevalence of violent victimisation was found among the SMI group (22.7% v. 8.5%). Compared with out-patients and patients in a sheltered housing facility, in-patients were most often victimised (violent crimes: 35.3%; property crimes: 47.1%). Risk factors among the SMI group for violent victimisation included young age and disorganisation, and risk factors for property crimes included being an in-patient, disorganisation and cannabis use. The SMI group were most often assaulted by someone they knew. Conclusions Caregivers should be aware that patients with SMI are at risk of violent victimisation. Interventions need to be developed to reduce this vulnerability.