BACKGROUND Self-harm in custody is a well-researched phenomenon. This is particularly true for women in prison who demonstrate disproportionately high rates of self-harm. Despite the growing body of prison research, there has been a lack of service user involvement (SUI). Aims To outline the first use of SUI in a custodial setting in developing care pathways for self-harm. METHODOLOGY A participatory action research approach was used to engage women prisoners and staff. RESULTS Participants were able to identify strengths and weaknesses of current care pathways and offer suggestions for service development based upon their experience of receiving and delivering care. CONCLUSION The authors conclude that despite participatory approaches being in their infancy in prisons the engagement of service users when aimed at effecting positive change can be successful.