The paper in two parts constitutes the first attempt at providing a comprehensive and primary source-based discussion of the Apfaltrers’ medieval history. Throughout its nearly seven centuries-long existence, the family had an important bearing on the destiny of Slovenian territory and left an indelible mark on it. It had the closest affiliation with the former province of Carniola, whence it also spread to Styria very early on. Its modest beginnings in the ranks of the Spanheims’ ministerial nobility were followed by a gradual social ascendancy, which, from the fifteenth century onwards, enabled the Apfaltrers to form part of the Carniolan noble elite. In spite of not attaining the highest offices in the provincial princely administration during the Middle Ages, members of the family played an important role at local level. Even though the family’s genealogical composition is not entirely clear, it is possible to recognize the existence of two main lines at least from the mid-fourteenth century onwards. The first part of the paper deals with the beginnings of the family and the Roje family line.