The paper deals with the issue of Yugoslav ideology and its role in suppressing the Serbian Cyrillic script. There were two different approaches in the concept of Yugoslavism as developed on the grounds of Illyrism (Lj. Gaj) in the midnineteenth century: the Croatian and the Serbian ones. The Croatian Yugoslavism (J.J. Strossmayer) was of a pro-Catholic and anti-Serbian character language and writing, it was manifested through annulling of Serbian language in the domain of "Croatian state legislation" and supression, prohibition and persecution of Serbian Cyrillic script. On the other hand, Serbian approach to Yugoslavism (T. Pavlovic, J. Subotic etc) was a tolerant one: the lingual diversity of the south Slavic peoples opposing the need for their co-operation. By the beginning of the 20th century the Croatian variant of Yugoslavism (with its three-tribal nation concept) prevailed over the Serbian one and became the grounding ideology for the new, common state. Its lingual union basing on the domination of the eastern ? ekavian ? pronunciation variant (from the Serbian language) and Latin letters (from the Croatian) was disadvantageous to both spoken and written Serbian language: the Serbs have accepted Latin writing and the Croats have never accepted the so-called eastern pronunciation. The consequences have not for diminished the Serbian Cyrillic script with the decline of the Yugoslav ideology (which was first abandoned by the Croats) nor with the falling apart of the Yugoslav state.