ENThe article is an introduction to research on epidemic diseases that occurred among members of the Radziwiłł family in the 18th century. I base in it on ego-documentary sources; lists, travel diary and diaries. Among the authors of the sources were: Karol Stanisław I Radziwiłł, Michał Kazimierz Radziwiłł ,,Rybeńko'', Teofila from Radziwiłł Morawska, Hieronim Florian Radziwiłł, Michał Hieronim Radziwiłł and Luiza Radziwiłł. The aim of the article is to present information that XVIII-century authors contained about the incidence of epidemic diseases. During the analysis of sources, I paid attention to such issues as the duration of the disease, causes of diseases, course and treatment methods and possible fatality result. In the further stage of research on this issue, it is worth using the wider source base and making the problem more statistically, using not only the diary, but also other sources treating this topic. The examples will contain information about the diseases of the authors and their relatives being members of the Radziwiłł family.