In many industrialized countries ethicists and lawyers favour advance directives as a tool to guarantee patient autonomy in end-of-life-decisions. However, most citizens seem reluctant to adopt the practice; the number of patients who have an advance directive is low across most countries. The article discusses the key argument for seeing such documents as an instrument of self-interpretation and life-planning, which ultimately have to be interpreted by third parties as well. Interpretation by third parties and the process of self-reflection are conceptually linked by a qualitative concept of identity. Identity is conceived here as constructed in a processual dialogue between a personal and a cultural perspective. How the cultural dimension comes into play in understanding the motivation, rejection or content of wished for end-of-life-decisions, is shown by a brief review of empirical and cultural studies. Understanding advance directives as a culturally embedded tool of self-interpretation should help to overcome urgent moral problems in clinical settings: how to interpret such documents, how to deliberate on the content and on the best form.