After World War II the development of special (auxiliary) historical disciplines in Lviv was determined by a number of features, including significant changes in the personal composion of their researchers. Some Polish and Ukrainian scientists, who have studied these disciplines, left the city. Instead, some Ukrainians, who had been living in the Ukrainian ethnic territories that have been transmitted to Poland after 1945, were repatriated to Lviv. Among these Ukrainians was a former teacher Ivan Zayats (1887–1968). He has graduated the Faculty of Philosophy of Lviv University (1913), where he had studied history and geography. During the interwar period (1920s – 1930s) he was a teacher in secondary schools in Peremyshl, participated in the cultural and educational life of the local Ukrainian community, was a co-organizer of The Ukrainian regional museum “Stryvigor”. Iv. Zayats has got a job at the Lviv State Republican Historical Museum in August 1946. At this museum he has worked as a researcher and chief custodian of its funds fifteen years. The museum was established by merging several Lviv museums and big local collections in May 1940. After that, this museum has become the owner of the largest collection of coins and medals in the city. Famous Polish museologist Rudolf Menkitskyj was the first who has carried out the work on their arrangement. The next who worked with coins and medals at the museum in 1944–1946 was Marjan Haisig, a former researcher at Lviv University. Iv. Zayats worked with numismatic collection of this museum at 1946–1961. He carried out an inventory, conservation and restoration of old and newly acquired materials, prepared indexes, selected some coins and medals for the museum exhibitions. He also started his scientific work in the field of numismatics at that time. In the 1950s the object of his scientific interests was the Lviv mint of the XIV–XV centuries. As the result of these studies he prepared an article in 1957. The article would have been to be published in the museum`s edition, which called “Reports and notices of the [Lviv State Historical] Museum”. This edition was never published due to a number of objective and subjective factors. Iv. Zayats’ article was not published either, although its content was known to some Lviv historians. We have find the typescript and pre-editions of this work (the text of Iv. Zayats’ article is given in the second part of our publication). The exploring of this article allows us to agree with the positive assessment of this scientific work, which was made by the former head of the Museum of Sphragistics and Numismatics of Lviv University Ivan-Julian Shpytkovskyj. It seems interesting Iv. Zayats’ attempt to consider the issue of issuance and circulation of coins of Lviv minting of the 14th – 15th centuries in the broader context of the changes that affected the Halycian-Volyn lands at this period. Also interesting his attempt to look at the status and relation of the Halychyna state to the Polish and Hungarian kingdoms through the prism of numismatics. Iv. Zayats, in particular, agreed with the opinion of some researchers who have spoken of a personal union between Halychyna and Poland during the reign of King Сasimir (Kazimierz) III and denied the fact of incorporation of Halychyna into Poland. He also wrote about the politically undefined status of Halychyna in relation to Poland and Hungary during the reign of Prince Wladyslaw of Opole and the next transformation this state into an ordinary Hungarian province during the subsequent reign of King Louis (Ludovic) of Hungary. According to Iv. Zayats’ article, the appearance of a Polish eagle on the coins minted in Lviv and the cessation of the issuance of a separate Rus coin in Lviv, was a sign of closer unification of Halychyna and Poland during the reign of King Wladyslaw II Jagiello. At the article listed the types of coins minted at this time in Lviv, presented their images and legends, draws a conclusion about the possible time of cessation of work the mint in the city. At the present time the scientific value of Iv. Zayats’ work reduced after research by Mykola Kotlyar, Stanislava Kubyak and Andriy Kryzhanivskyj. However, now it remains as an interesting monument of Ukrainian historiography of special (auxiliary) historical disciplines of the 1940s and 1950s.