Purpose -The purpose of this paper is to explore the effectiveness of Eye Movement Desensitisation and Reprocessing (EMDR) therapy in an individual with mild intellectual disabilities currently compulsorily detained in secure care. Design/methodology/approach -The intervention utilised the EMDR eight-phase protocolised psychotherapeutic approach. Sessions utilised symbol cards to explore the impact of the client's experiences in relation to his thoughts, emotional feelings, physical feelings and behaviour. Drawings were also utilised to assist the client to develop a picture of the traumatic incident. A "safe place visualisation technique" was also utilised at the end of every session to manage any distress. The Posttraumatic Stress Diagnostic Scale (PDS) with some minor adaptations for use with people with intellectual disabilities was utilised as a pre-and post-measure. Findings -The study identified reductions in symptoms in all three core clinical subgroups of the PDS: re-experiencing, avoidance and arousal, with outcomes being maintained at one-month and six -month follow-up. Reduction in the strength of ratings was most evident in the avoidance domain. Originality/value -There are limited studies exploring the effectiveness of EMDR with individuals with intellectual disabilities.