Parents of young adults with mental illness may face a continued demand for support, even though their children have reached the age of majority. The aim of this study was to explore relatives' experiences of parenting a young adult with mental illness in transition to adulthood. Individual interviews were conducted and analysed according to Grounded Theory. The results showed that relatives experienced powerlessness and a sense of inescapable duty with limited possibilities to be relieved. With a family nursing approach, relatives can be supported and, when the young adults' needs of care are met, they can be relieved from their burden of responsibility.