In the paper, the author presents the archive and the records of the Rein Monastery; the oldest still exsisting Cistercian monastery, which was founded in 1129 and houses the largest private archive in Central Europe. The preserved records mirror the activities of the Monastery, whose superiors as vicars general had control over subordinate monasteries (among others also over the monasteries of Stična and Kostanjevica). The records also shed light on the monastery's economy, considering its role as a large land owner whose property from 13th century on extended all the way to the Slovene Styria and Lower Carniola as well. The records, among which many can be used for the study of the Slovene past, are presented in three basic categories: charters, books (manuscripts) and documents. At the end, the author provides regests of chariers (74 original charters, transcripts or regests), of which 22 original charters and 10 transcripts or regests have up to now never been published and deal almost exclusively with the Rein vineyards near Ljutomer and Gornja Radgona.