This article examines the relationship between the Brussels painter Jan 11 van Coninxloo (ca. 1489-1561 or later) and the Benedictine convent of Groot-Bijgaarden. In earlier publications by J. Maquet-Tombu the link between certain members of the Van Coninxloo family and the Vorst convent have already been pointed out. A new chapter can now be added. In the archive of Groot-Bijgaarden convent are two books in which payments made by the prioresses Françoise and Catherine van Straten for the dccoration of the convent and the church are recorded. The books list a separate item for painting and polychrome work. Here, for the first time, the name Jan van Coninxloo crops up in connection with a sum paid for painting the side panels of the main altar. Van Coninxloo was also paid for painting organ doors, a vaulted ceiling and for 'rough painting'. Four triptychs by Van Coninxloo have also been preserved; they were commissions from women of noble birth who had taken the veil. The names of three of these nuns are known: Anthonine de Locquenghien, Berbel van dcr Noot and Marie Brant. The fourth was called Barbara (Berbel). In view of all this material it may be concluded that Van Coninxloo played a significant part in the decorative appearance of the convent church. He was responsible for triptychs on altars dedicated to St. Anne, St. John and St. Benedict. He also painted the smaller triptych with the Seven Sorrows of the Virgin, the panels of the high altar, doors for an organ and (part of) the ceiling decorations. The article offers a new insight into the context of a group of paintings and adds a number of works to Jan 11 van Coninxloo's oeuvre.