Purpose - Dialectical behaviour therapy (DBT) has been widely used in a number of different settings with published outcomes and literature supporting its validity and efficacy. What is less understood is DBT's application to forensic populations. The purpose of this paper is to qualitatively explore the experiences of high risk and adult male forensic clients (diagnosed with borderline personality disorder (BPD) and antisocial personality disorder (ASPD)) in a forensic adapted version of DBT. Design/methodology/approach - Six clients who had completed four modules of DBT and individual therapy engaged in semi-structured interviews which were transcribed and analysed using thematic analysis. Findings - The findings identified emerging themes relating to group processes and treatment outcomes. Specifically, the importance of motivation, shared learning, professionalism, reinforcement and reflection in creating a positive experience of DBT were identified. In addition clients identified feeling supported, a sense of belonging, personal achievement, increased knowledge and skills application as being part of their experience of DBT. Research limitations/implications - Whilst efforts were made to manage limitations, potential confounders include the impact of the researcher's direct involvement in the facilitation of DBT and the small sample size. Practical implications - This study provides support for the use of DBT with forensic males diagnosed with ASPD and BPD and the importance of the group component to the treatment modality. It emphasises the importance of group cohesion and the development of interpersonal factors including feeling supported, sense of belonging and a sense of achievement. Originality/value - This paper provides a unique contribution to the understanding of the application of DBT with forensic male clients with personality disorder. It is the first known study to use qualitative methods to explore forensic male clients' experiences of group and individual DBT. This paper provides insight into the key themes of clients' experiences of DBT. These identified themes lend support to the importance of motivation of clients and the experience of shared learning, reinforcement and reflection. Furthermore, feeling supported, having a sense of belonging and a sense of personal achievement were identified as key to the positive experience of clients.