In this article Philippe Lejeune presents his own interpretation of a personal diary as a specific written practice which each day organises an interplay between life and writing, allowing one to direct one’s existence with keeping a record of it. According to the author only on the secondary level can the diary become a work of literature. He emphasises the importance of reaching real, original journals (together with the particular material existence) and those keeping the diaries (asking them the reasons for keeping the diaries and the way in which they do so) and not simply analysing published diaries – which is what usually happens in works on their subject. Lejeune briefly describes the history of his own research into such diaries and specifies the three most import forms of such research – a questionnaire completed by a group; an appeal for evidence to specific people and an interview with the person keeping the diary. He also points out the problems created by the use of these methods in countries with different traditions and cultures (France, Spain, Russia, Algeria).