Healthcare policies often state that complex conditions are to be treated outside hospital in various forms of public-private partnership. Chronic obstructive pulmonary disease ( COPD) is a progressive illness that includes episodes of serious acute exacerbations characterised by extreme breathlessness. There is limited knowledge about COPD exacerbations from the perspective of family caregivers and implications of the changing boundary between hospital care and care at home. In this paper, we explore how caregivers negotiate their role as caregivers with patients and healthcare professionals during acute exacerbations. We conducted 10 qualitative interviews with family caregivers of COPD patients in 2011, all were spouses over the age of 60. The participants were recruited through the patient pool of ambulatory pulmonary services of two hospitals in Oslo, Norway. Data were interpreted using thematic analysis. The caregivers described a lack of understanding and support from health professionals in some situations. They shouldered considerable responsibility, but were not always acknowledged as competent carers by professionals. Caregivers had to balance their involvement. They noted that they could lose the professionals' co-operation if their involvement was perceived as interfering or preventing the professionals from exercising their expertise. However, by not sharing their personalised knowledge about the patients, they risked that the professionals would not understand the severity of the exacerbation, which could undermine their own ability to maintain a sense of safety and control. The negotiations caregivers participated in and the uncertainty they experienced shed new light on the complexity of their role, and the discrepancy between practice and ideals in healthcare policy regarding collaboration of care. It is crucial to develop further knowledge about structural, interactional and communicational facilitators and barriers for reaching shared understandings and facilitating mutual trust in these demanding situations.