ENJonas Bretkūnas is one of the most important personalities of old Lithuanian writings, standing next to Mažvydas, Daukša, Sirvydas. Jonas Bretkūnas' Postilla is the first printed collection of Lithuanian sermons meant for evangelic Lutheran ministers working in the Lithuanian parishes in East Prussia. It was the biggest Lithuanian publication of the time in the whole of the Prussian duchy. It is composed of the extracts from the New Testament and corresponding sermons written for the whole church year. Two usage models of pronominal reflexives were typical of old Lithuanian writings: I, Lithuanian - the neutral usage of the reflexive pronoun in terms of person, number and gender categories; II, non-Lithuanian - the reflexive usage of non-reflexive pronouns in the sphere of first and second person; reflexive forms in this case are used only in the sphere of third person. In the pericopes of Bretkūnas' Postilla, the second model more than 10 times exceeds the first one. While in sermons, the first model is used slightly more often. Such ratio between the constructions of the different models in the texts of the sermons and pericopes can be explained by a different level of the originality of the sources. All extracts from evangels have come from classical languages (directly or via Polish or German), in which the usage of the reflexives differs from the Lithuanian language. That is why the prevalence of the second model in pericopes is totally understandable. The sermons were written in Lithuanian; that is why the abundance of the constructions of the first model is quite regular. It has to be emphasised that such usage of the reflexives of the first model singles out Bretkūnas' Pustilla from other Lithuanian writings of the 16th-17th centuries. It testifies to the immaculate sense of Lithuanian possessed by Bretkūnas and the closeness of his syntax to the vernacular language of the Lithuanian people.