Aim: The overall aim was to create knowledge about what it means to live with bipolar disorder from an existential perspective, both for individuals with the diagnosis and for their close relatives. Method: An existential perspective in this context entails that it is explored and described from a lifeworld perspective of individuals who in various ways experience that which is termed as bipolar disorder. The lifeworld phenomenological approach Reflective Lifeworld Research (RLR) was used in the four empirical studies. Meaning-oriented interviews and analysis were conducted following the leading methodological principles of the chosen scientific approach. A synthesis, based on lifeworld hermeneutic existential philosophy, then presents how it is possible to understand the perspective of individuals with bipolar disorder and their close relatives as a coherent whole. Findings and conclusions: A magnitude and complexity of experiencing, which means that life with bipolar disorder is characterized by extra dimensions, specific tension and contradictions, has been elucidated. Knowledge of the meaning of these aspects enables for the persons with the illness and for their close relatives to understand, to put words to, and to communicate how their life is and what they need, which in turn enhances their ability to influence their lives. It also increases the opportunities for professional caregivers to develop care, both in content and organization, so that it can meet the actual needs of those concerned in an adequate way. Living with bipolar disorder means so much more than the usual description with changes between episodes of depression and mania. The diagnosis “bipolar disorder” thus appears to be an inadequate label that only reflects the more obvious and visible dimensions of the illness, while those that characterize life in its entirety remain hidden. The thesis also shows that the importance of the common everyday life of persons with bipolar disorder and their close relatives should be highlighted as the most important factor in a liveable existence. A change in the view of mental health care is thus needed; a change that is characterized by consensus, collaboration and transparent communication between the person with the illness, their close relatives and mental health care. The common goal should be about meeting actual needs, and to strengthen a profound connectedness in order to make everyday life more liveable.