ENIn our time, the young in Europe need help, through clear and concrete exemples, in understanding that almost all the modern languages of the continent (the Indo-European areal) trace their origins back to the IndoEuropean ancestor language. A considerable use of the Greek and Latin languages in comparative linguistics reminds us of what importance those ancient cultures are to us, especially in linguistics. In studying the origin of the Lithuanian (Baltic) words, one usually refers to the roots of the Indo-European ancestor language. The French language traditionally bases itself on the Latin language, with only a few linguists getting back to the Indo- European ancestor language. Thus, the article aims at presenting a scientific comparative study of not only clear similarities among the Indo-European, Latin, Greek, Old Baltic, Lithuanian, French and other languages but also drawing researchers' attention towards more specific and detailed aspects of studies beyond the scope of the present article. The findings of the study indicate that a number of grammatical categories in the above mentioned languages are easily compared, while others comparisons are more problematic, the categories being somewhat different.