V.Vernadsky assigned a great importance to his 'genetic links' with Ukraine, being concerned with Ukrainian history, culture, his family genealogy. He believed organization of the Ukrainian Academy to be his most successful affair. A vast stock of his epistolary heritage, including his diaries, represents a valuable source on the history of the Ukrainian science, including the Ukrainian Academy. Now this stock can be better accessed thanks to the project 'Library of Works of Academician V.I.Vernadsky', fulfilled in the Russian Academy of Sciences in 90s. However, large stocks of materials remain unpublished. The article contains passages from Vernadsky's letters showing Vernadsky's judgments of scientists who were earliest members of the Ukrainian Academy of Sciences (UAN), and of others who communicated with him during his stay in Kiev. As seen from Vernadsky's writings, the main criterion of his judgment was one's implemented research potential, although organizational qualities were not disregarded as well. The examples of Vernadsky's opinions on K.Timiryazev - distinguished Russian biologist, M.Grushevsky - outstanding Ukrainian historian, and on other Ukrainian scientists engaged in establishing the UAN confirm that his judgments tended to be rigid but objective. Also, Vernadsky's opposition is shown to political speculation and partiality, emotionality and national ambitiousness of certain Ukrainian scientists representing the earliest generation of the Ukrainian academy science.