PurposePatients in the National High Secure Healthcare Service for Women have a high prevalence of trauma and self injury. This highlights the need for specialised training of staff dealing with such women. The aim of this study was to evaluate the trauma and self injury (TASI) training programme on staff knowledge and skills.Design/methodology/approachA total of 135 nurses and nursing assistants participated in the TASI two‐day training course. Questionnaires allowing for quantitative and qualitative data collection were completed before and after the training. Training and confidence levels in dealing with women who self‐harm prior to the training were identified and the impact of the programme was assessed.FindingsThe majority of staff had not received any previous training on trauma and self injury. There was an increased level of confidence in working with trauma and self injury following training and staff reported an increased ability to ask for support. Self‐perceived competence improved to a greater extent in those who had not received previous training compared to those who had.Research limitations/implicationsThe authors' data is limited to self‐report. Future research should use objective measures to evaluate the impact of staff training.Practical implicationsA relatively short training programme focusing on trauma and self injury appears to improve staff confidence, understanding and competence in working with women patients in a high secure setting. Similar training programmes might also be beneficial in different patient groups with complex backgrounds and behaviours.Originality/valueThis is the first report on a training programme focussing on women in high secure care who self‐harm and have experienced trauma.