The article discusses Lucyna Sadzikowska’s book entitled Listy z lagrów i więzień 1939–1945. Wybrane zagadnienia (Letters from the Concentration Camps and Prisons 1939–1945. Selected Issues. Katowice 2019). According to the author of the article, the published letters of the inmates kept in concentration and labour camps remain interesting descriptions of the camp reality that redirect the reader towards literature of the personal document. The purpose of Sadzikowska’s book is to describe and codify the prison and camp letter with regard to its theoretical and practical aspects. She analyses and elaborates on official and unofficial camp and prison correspondence (e.g. secret messages, letters smuggled in or out of camps and prisons), and presents a peculiar supplement to this epistolography, i.e. the literary letters of Gustaw Morcinek. The reviewed work not only presents the author’s commitment to elaborate on camp and prison epistolography written in the period between 1939 and 1945, but also points out the inspiring potential of personal documents.