ENGreeks played an impressive role in the Lvov and Vilnius fellowships as practically until the end of the XVII century (1685) jurisdictionally the Church on the territory of the Commonwealth (Kievan Metropoly) was under the authority of the patriarchate of Constantinople. The fall of Constantinople in 1453 did not immediately stimulate the Greeks to search support from their brothers in the North, therefore they came to the Commonwealth only at the end of the XVI century. At that moment they transferred to Poland, among other things, their own experience of Church education. Former contacts of Greeks with the Commonwealth concerned mostly the monasteries and only patriarch of Antioch, Joachim V Dau sent in 1523 his first delegation to Moscow which – like all the next ones – usually stopped on their way in Lvov and Vilnius. Patriarch Joachim on the 11 (1) January 1586 issued in Lvov the charter in which he approved the new statute of the Lvov fellowship. Patriarch reformed the Lvov fellowship and used it to introduce reforms in the Church on the territory of the Commonwealth. Among other things, the new statute allowed to accept in the fellowship, apart from the townsmen, also persons of noble birth or plebeian descent; withdrew the fellowship from the jurisdiction of the local bishop and raised it above the existing hierarchy. The new statute of the Lvov fellowship as well as that of the Vilnius fellowship of 1588 granting the stauropegial status (the next patriarch Jeremiah II) was confirmed in 1592 by the privilege of king Sigismund III Vasa. One can clearly see that in the privilege granted also to the schools of Lvov and Vilnius fellowships the main emphasis in the education was put on teaching languages: Greek, Church Slavonic, Russian, Latin, Polish. They were also teaching grammar, poetry, rhetoric, dialectics, elements of philosophy, logics, arithmetic, music, geography, and astronomy.Obviously the classes in the schools of Lvov and Vilnius fellowship were linked with the Church life, so they also taught structure of the Church, reading and understanding the Holy Scripture, liturgy, tradition and the teaching of the Church Fathers, lives of the saints, church singing. One cannot help mentioning here the activity of another Greek – protosyncel Cyril Loukaris, who came to the Commonwealth sent by the patriarch of Alexandria, Meletios Pigas. The participation of the Greek lecturers had a significant input in the formation of the education in the schools of Lvov and Vilnius fellowship. Cyril Loukaris was the dean of the Vilnius fellowship school, Arsenios organized and created the whole educational programme in the Lvov fellowship school. Arsenios was the first teacher of Greek in the Lvov fellowship school. Later on his didactical work was supported by Cyril Loukaris, Meletios Pigas as well as by the exarch of the patriarchal throne, archdeacon Nikephoros Parasches-Cantacuzene. Arsenios committed himself to creating a teaching programme for the fellowship school. Evidently he used here as a model the well-tried Byzantine education that he knew from his own experience. We can assume that Cyril Loukaris, who taught in the Ostrog Academy as well as many Greeks who worked there (Dionysios Rallou – metropolitan of Kizikos, Emmanuel Achilleos – a religious polemicist, monk Theophanes, Eustathios Nathanael, Emmanuel Moschopoulos) many times offered their assistance to the Lvov fellowship school. Greek patriarchs, i.e. Joachim V Dau and Jeremiah II, granting the fellowships the rights and privileges, made them more independent and better organized.Greek teachers understood perfectly well the value of the fellowship schools in the development of the orthodox society and church life in the Commonwealth. Graduates of those schools became later priests, dyaks, psalmists, teachers in the fellowship, court, parish and mo nastery schools. The most eminent of them were active religious polemicists and church activists. The fellowship schools largely contributed to the defence of the rights of the Orthodox Church in the Commonwealth and increased the religious and national consciousness of the Ruthenian population. Keywords: schools of Orthodox Fellowships, Lviv, Vilnius, Greek Lecturers.