Self-care is interpreted from a health economic point of view. Various approaches are presented. It is stressed that the decision-oriented approach used by other health service researchers is an integral part of the economic approach to the topic as is the idea of a continuum of care, from self-care to professional care. A new approach is taken to the modeling of self-care, in that self-care becomes part of a four-part demand for care model. This makes it possible to model the demand for care for three different groups separately: 1--persons with zero episodes; 2--persons with pure illness episodes and illness episodes with self-care; 3--persons with episodes involving professional care or professional care combined with self-care. Another contribution is due to the so-called episodic approach to the demand for care. The natural counting units are illness and treatment episodes, i.e. instead of counting for instance number of times a general practitioner is consulted we ought to count the number of episodes involving professional care, self-care or both types of care. The episodic approach seems to be well suited for work with self-care. The empirical part is based on a unique Danish panel study using health diaries returned weekly. Data from 27 of the 52 reporting weeks are used, involving more than 14,000 episodes distributed across about 2800 persons belonging to about 1000 households. The use of health diaries seems to be very well suited to the study of self-care in that less salient events and activities than professional care are picked up far better in prospective health diary studies than in retrospective questionnaire based surveys. Descriptive and regression (logistic and ordinary) results are presented.