Antvorskov was the principal Scandinavian monastery of the Roman Catholic Order of Saint John of Jerusalem, located about one kilometer south of the town of Slagelse on Zealand, Denmark.
In 1165, Valdemar the Great, who was himself an honorary Knight of St John, gave the Order land at Antvorskov. The monastery (Danish:kloster) was constructed soon thereafter, during the time of Archbishop Eskil. The mother monastery, on Rhodes, and a monastery on Cyprus were built to house pilgrims to the Holy Land. Daughter houses such as Antvorskov were to forward any profits from properties to the monastery on Rhodes. Over time, however, especially after the collapse of Crusader kingdoms in Palestine, the Order focused more on helping local people, especially those suffering from leprosy, which was not uncommon in medieval Europe.
Antvorskov served as the Scandinavian headquarters of the Order, known also as "the Hospitallers", and the prior of Antvorskov reported directly to the great officer of the Order in Germany, the Grand Master of the Order on Rhodes (and, later, on Malta), and the pope. As a result, Antvorskov was one of the most important monastic houses in Denmark. Before the Reformation, its prior often served as a member of the Council of State (Danish:rigsråd) as well.
In the thirteenth and fourteenth centuries, the monastery became one of Denmark's major landowners. Many persons nearing death and seeking to withdraw from the world into a quasi-religious life donated some or all of their goods to the monastery. Many families seeking heavenly rest for their kinsmen donated property to buy prayers in perpetuity for those deceased relatives, or to buy burial places inside the abbey church.