The issue of information potential of the Ukrainian press of the first forty-years of the 20th century as a source of data on Ukrainian print media of the indicated period is highlighted. The survey of a number of newspapers and magazines issued at that time in different regions of Ukraine (in such cities and towns as Ielisavetgrad, Kyiv, Lviv, Skvyra, Sokal, Odesa, Khorol, and so on) and abroad (Vienna, Ekaterinodar, Paris, Prague, Ruski Krstur, Scranton, Tashkent, Harbin, and others), is made. The materials on the history of Ukrainian press were selected, their analysis was performed. Conditional groups of these publications are defined: 1) promotional and organizational materials; 2) bibliographic lists; 3) press studies related publications; 4) biographical materials; 5) re ports on the activities of various institutions. Their content is studied; a number of examples are given. It is noted that the Ukrainian press of the first four decades of the 20th century contains important data on the history and bibliography of individual journals, groups of publications (by place, year of publication, type, specialization, and so on) as well as the system of Ukrainian print media in general. In particular, this article shows that the studied materials help the modern researcher to elucidate purpose and objectives of specific media objects, to establish reasons for their creation/closure, the circle of employees/ authorship, publishers and, last but not least, real editors. It is elucidated here that some publications contain information about the circulation of periodicals, the amount of royalties, editorial policies aimed at expanding the readership, content of publications, and so on. The value of such data for reconstructing the history of the unpreserved print media is emphasized. It is noted that the pages of the studied newspapers and magazines contain information about press projects, which implementation has yet to be verified. It has been stated that the study of materials of the thematic direction published in the press during the first forty years of the XX century contributes to the reconstruction of the history of particular media objects and the history of the Ukrainian journalism of that period in general. Keywords: press, information potential, source of studying the history of mass media, Ukrainian print media, history of the journalism.