The monograph ('Theology of the Reformer Primož Trubar') deals with the theology of the reformer Primož Trubar and thus fills the only major research gap in the study of works written by the important Slovenian Protestant. Gerhard Giesemann’s approach to Trubar’s role in present Slovenian (national) context and his original role in the 16th century is a theological one. The author discusses the question of sources of Trubar’s theological writings and the question of their originality. For this purpose, he analyses primarily Trubar’s catechisms, Slovenian and German introductions to biblical translations and the Church order. On the basis of comparison of various Protestant theological texts, the author states that Trubar in almost every way faithfully based his thought on Martin Luther, his collaborators Brenz, Melanchthon and Dietrich, and the Wittenberg Reformation. While explaining the Letters of Paul, Trubar adopted Luther’s interpretations of the justification by faith, law of Moses, grace, original sin, human nature, Christology etc. The importance of Trubar’s theology does thus not lie in the originality of its content or its inclination to Zwinglianism, as maintained by older researchers, but in the originality of a way of explaining the Lutheran dogmas to Slovenian people.