An opinion that old Serbian literature has not studied poetic properties of particular genres, because it has no sufficient knowledge on epistolary literature, induced us to investigate on the subject. The strivings of antique rhetoric and the perfection of evangelic teaching, are permeated in the artistic adaptation of this genre. An opinion of the oldest church fathers and writers on the epistles, as a specific form of epistolary genre has been spread among all Slavic people due to the influence of the early Byzantine literature. Essential properties - conciseness, clarity, closeness to nature, as a result of artistic achievements of the Old fathers' writings have become a stylistic criterion of epistolary genre of old Serbian literature. We have started this paper with the epistles concerning life of the monks, their accomplishments through the world of holy secret and the virtues, their thoughts of salvation, moving towards the point of view from which one understands psychological and ideological level of presenting a character. Thus, it can be seen how through longing and benefactions God calls into eternal life, how through holy evangelic virtues human soul is transformed, 'becomes rooted in love' (Eph.3,18) fulfills with 'strivings towards heavens dwelling' (Phil.3). Other properties of Byzantine epistolary literature also had, apart from the poetic forms and stylistic characteristics, a very strong influence on this genre of Serbian literature. Some dogmatic issues, connected with orthodox theological teaching were often a subject of the epistles, evangelic teachings of the holy secrets and virtues, fasting and prayer, as well as Holy Fathers opinion on it, were interwoven in to the epistles with an aim to teach the interlocutor. In the most part of the epistles of old Serbian literature the subject is elevated thus an artistic treatment of this subject demands creative attitude from the author, which takes him on to the horizons of contemplating God inspired method of addressing people, the one found in the writings of the Holy Fathers of the Eastern Church.