Although in recent years there has been an upsurge in the research of the history of early modern spirituality, this research has paid hardly any attention to the Unitarian denomination. The reasons for this lie beyond the scope of the present study: between the late 16th century and the late 18th century the denomination had to refrain from the use of printing, and thus, the manuscript versions of prayer texts were threatened by loss and destruction. It is a unique paradox, however, that the first edited protestant Hungarian prayer book of considerable length was published precisely by this denomination in 1570/1571. The first part of the paper explores the concept of the prayer book based on Johann Habermann’s famous Gebetbüchlein, and compares it to the greatest achievements of the same sort within this period, the Catholic Péter Pázmány’s and the Calvinist Albert Szenci Molnár’s works. This section is followed by a survey of the vivid reception of Heltai’s work, with particular focus on the way the Unitarian author’s work was used in the Lutheran community of Lőcse. The concluding part argues that building on the foundations of this tradition, as well as on the heritage of Calvinist prayer culture, an unparalleled Unitarian prayer literature developed in the 17th-18th centuries, which deserves the attention of comparative research.