Little is known about the perceptions of sibling relationships from the direct perspective of service users with mental health difficulties; this study aimed to address this gap. Semi-structured interviews were carried out with adult male inpatients who had severe and enduring mental health difficulties. Interpretative phenomenological analysis was used to analyse the data and revealed three main themes: (1) The closeness of the sibling bond; (2) The change in sibling dynamics following diagnosis and admission; (3) Siblings' contribution to mental health and recovery. The implications of involving siblings in care and the benefits of service user led research are discussed.