ENProf. Jadvyga Čiurlionytė (1899-1992) is known as one of the most important and actual personalities in Lithuanian ethnomusicology. Her writings are known for all the Lithuanian ethnomusicologists as the main and basic studies on Lithuanian traditional musical folklore. Anyway, works of J. Čiurlionytė are almost completely unknown for West-European ethnomusicologists. There are no original writings or any other way published translations by J. Čiurlionytė in English, German, French or any other European language, where the main original scientific achievements of J. Čiurlionytė are reflected. We have to comment some quite special circumstances, caused and determined the scientific situations, points of view, fields and directions of J. Čiurlionytė scientific activities. J. Čiurlionytė started her ethnomusicological writings in 1930-ies in Kaunas, Independent Lithuania. It was no in fashion to print any Summary or Abstracts in English or German in the monographs at those times. And the most actual her writings were published in Soviet times, when it was impossible to publish any writings in any Western language.The special situation of comparative ethnomusicological studies. All the writings of J. Čiurlionytė were based on Lithuanian musical folklore, especially folk songs. She was not able to get any materials for comparative studies with the writings of Western ethnomusicologists. We have just to admit the very important and detailed comparative studies of J. Čiurlionytė, based on the Lithuanian Dzūkija, Aukštaitija, Žemaitija ethnic regions and historical Lithuania-Minor (Prussian Lithuania) region.Western ethnomusicologists use to give a great attention to the social context of the folklore life and its developments. But the clear folk singing tradition is described as connected with some rituals or not connected with them. So, folk songs are classified as ritual or non-ritual mostly without special attention for their genre classification. J. Čiurlionytė developed this classification system quite deep way. J. Čiurlionytė used almost 30 ritual and over 50 non-ritual Lithuanian folk songs genres in her scientific terminology. Variability of the melodic lines. The great attention J. Čiurlionytė gave for the problem of variability and stability of melodic lines. She proposed the terms of melodic types, melodic variants (sub-variants) and melodic versions (sub-versions) here. The peculiarities of the most ancient melodic intonations of Lithuanian folk songs. J. Čiurlionytė always stressed the very important role of ascending and descending intervals in the melodic lines of Lithuanian monodic folk songs. As the most important intervals in formation of our folk melodic style she defined the ascending minor terces, perfect quarts and quints. Descending - minor and major seconds and minor terces. The most primitive musical scales. Problem of anhemitony and hemitony. J. Čiurlionytė stressed the importance of narrow-wide musical scales in the most ancient melodic lines. She showed clearly the historical formation of the well known in Lithuanian song-lore scales as g-(a)-b; g-(a)-b-c; g-b-c; g-(a)-b-c-d before the formation of Major-Minor scale system. She aalso showed the importance of trichordic and tetrachordic scales as an independent anhemitonic formations here.The basic steps theory in the scales of melodic lines. J. Čiurlionytė noticed, that similar melodic tunes use to have the same two (upper and lower) steps in the melodic scale there. Both basic steps are there in the intervals of major second, minor or major terce, perfect quart or quint as a rule there. Later on dr. G. Četkauskaitė developed this basic steps theory, and she described basic steps in major second, minor terce and perfect quart as the most typical in the most ancient melodic tunes of Lithuanian folk songs. The terminology of tunes with prim-tonal, second-tonal, terc-tonal, quart-tonal (etc.) basic steps was proposed by G. Četkauskaitė, following the remarks of J. Čiurlionytė. Metro-rhythmic studies. J. Čiurlionytė came to the conclusion, that melodic lines were much more stabile in the historical development of the variations, subvariations, versions and subversions of our folk songs to compare with the rhythmic patterns of poetic words here. The research studies on metro-rhythmic constructions of Lithuanian folk songs are still on the way to be continued from the point of view by J. Čiurlionytė. Melodic forms of Lithuanian folk songs. Those studies were also important in the writings by J. Čiurlionytė. She discovered the oneline, two-lines, three-lines etc. stanzas as the most ancient ones in the Lithuanian traditional song-lore. The main ethnomusicological discoverings, made by J. Čiurlionytė in 1930-ies - 1960-ies are the start points of a number of doctor dissertations at present and in future, in Lithuania and abroad.