In the last quarter of the 15th century, the movement of rosary brotherhoods developed dynamically in Dominican monasteries in Germany and Italy, as well as in Silesia, Western Pomerania and Kujawy. It was similar in medieval Lesser Poland, as evidenced by the text of the Krakow Acta Episcopalia of April 27, 1498, analyzed in this study. This text is the judgment of the bishop's court in the case of the rosary brotherhood operating in the Dominican monastery in Opatowiec. The presented source is the oldest known source regarding the activities of the Rosary Brotherhood in Lesser Poland. It also provides insight into the customs and popularity of this type of religious association.