Prolonged mental health problems of one family member influences the whole family system, including sibling relationships. The current research focuses on the way siblings of persons with mental health problems experience the relationship. The findings identify the challenges and difficulties these siblings face and can help mental health practitioners support siblings as well as their brothers and sisters with mental health problems. This qualitative research employs the Interpretative Phenomenological Analysis method. Data were collected through in‐depth semi‐structured interviews with 14 adult siblings of persons coping with prolonged mental health problems. The sample included seven men and seven women, between the ages of 20–55. Three main themes were identified: (a) Connection: Between involvement and distance; (b) Communication: Controlled confrontation or cautious vagueness; (c) Role: Positioning in the sibling relationship. The discussion introduces the Relational Dialectics Theory in order to understand contradictory statements that arise from the interviewees’ experience of dialectal tensions between: involvement versus distancing; direct confrontation versus cautious vagueness; and opposing positions in relation to the sibling coping with mental health problems. A multi‐voiced discourse allows for dialogue that incorporates the contradictory poles of the dialectic, thus enabling the siblings to balance the tension in the relationship. In addition, the concept of ambiguous loss is used to interpret the findings. The study is limited by the small homogeneous sample. The results highlight the need for practitioners to give special attention to siblings of persons with mental health problems in order to help them process and cope with the challenges in the relationship, thus providing an opportunity for growth and empowerment.