Aim To gain accounts of the functions of self-harm in a sample of adult male prisoners with mental health difficulties and to learn what they believed would help them reduce or stop their non-suicidal self-injury (NSSI).

Method A preliminary study involving six semi-structured interviews with male prisoners with mental health difficulties who had presented with NSSI and subsequent thematic analysis.

Results Four main themes were identified: affect regulation, affective change after NSSI, coping and mediators of NSSI. All participants cited affect regulation as the function of their NSSI and they discussed the impact of the prison environment on the behaviour. Participants indicated that medication and support networks could be mediators of NSSI. This study was limited by its small sample size, however, the findings indicate this would be a valid area for further research to gain greater understanding of NSSI in the prison population, providing the opportunity to consolidate themes.

Conclusion The findings highlight the importance of interventions targeting emotion identification, regulation and expression, and coping skills in prison environments. This is important because of the increasing rates of NSSI in the prison system in the context of resource pressures.