The background for this article is the centrality of the concept of self care to the management of chronic diseases. The article argues – based on a review of health professional journals and an anthropological study of patients – that the concept works as a boundary object in chronic care – i.e. the concept is simultaneously used as an unspecific, positive and shared denominator in interdisciplinary collaboration, as well as in specific and quite different ways in local settings. The open ended use is an obvious strength, since chronic care entails collaboration between different organisations, sectors and disciplines – and between the healthcare system and patients in their everyday contexts. However, when interventions have to be monitored and evaluated this becomes a major obstacle. The article concludes that seeing the concept of self care as a boundary object could open up new avenues for both analytical and practical work on self care.