Purpose. Empirical support for the predictive validity of North American actuarial violence risk assessment tools in Britain is lacking. The purpose of the study was to explore the validity of the Psychopathy Checklist: Screening Version (PCL:SV), Violence Risk Appraisal Guide (VRAG) and the Historical part (H-10) of the Historical/Risk/Clinical (HCR-20) scheme, in predicting in-patient violence in 87 mentally disordered patients in a medium-secure unit. Methods. Actuarial scores were obtained retrospectively from pre-admission/admission case records. The presence/absence, severity and frequency of in-patient violence was recorded by an independent researcher. The predictive accuracy and associations between predictors and outcome measures were evaluated using correlational analyses, regression procedures and receiver operator characteristics (ROC) analyses. Results. Scores on all three risk assessment tools were significantly higher in the violent cohort. The PCL:SV is the most robust predictor of in-patient violence, and contributes significantly to the predictive validity of the VRAG and H-10 scale of the HCR-20. Conclusions. The PCL:SV appears to be a valid predictor of in-patient violence within 12 weeks of admission to an English MSU and predictive validity is similar to that reported in North American studies.