Dual diagnosis (the combination of mental health and substance misuse problems) is a significant facing mental health nurses in the UK. The purpose of the study was to describe the lived experience of community mental health nurses working with people who have a dual diagnosis. A phenomenological approach was us and a purposive sample of seven community mental health nurses with experience of working with people with a dual diagnosis was selected. Data were collected through audiotaped, semi-structured interviews lasting approximately 1 h in duration and analysed using Colaizzi's (1978) method. Thirteen theme clusters relating to three major themes were identified: (1) difficulties in understanding the concept of dual diagnosis; (2) feeling deskilled when working with people who have a dual diagnosis; (3) struggling to work in a system which seeks to avoid people with dual diagnosis. Recommendations regarding the need for increased joint working between professionals, improved education and further research are made.