The Portrait of a lady purchased in 1872 by the Koninklijke Musea voor Schone Kunsten van België [Royal Museum of Fine Arts of Belgium, Brussels] as a work by the Dunkirk painter Jean de Reyn (1610?-1678) is actually by Jan Pietersz. van Rijn, who in 1620 was registered as a member of the guild of Saint Luke at The Hague ('s-Gravenhage). For stylistic reasons the authorship of Jean de Reyn has frequently been doubted in the past. He occurs as a pupil of Antoon Van Dyck in Descamps. His surviving œuvre - chiefly in Dunkirk (France) and its surroundings - displays a pronounced Rubenesque slant in its composition and style. It was difficult to unite to this the "Dutch aesthetic" which Fierens-Gevaert thought to recognise in the portrait of a lady in the KMSKB (cf. the 1913 museum catalogue). Nevertheless, the portrait is listed under the name of the Dunkirk painter to this day. The somewhat enigmatic signature "J. en JANRIJN" was the deciding factor for this attribution. However, a fresh light was cast on the affair by the discovery of an earlier sale catalogue dating from 1868 in which "RYN (Jan Pietersz Van)" appears as the artist's name. That four years later, in the auction of 1872, the portrait was wrongly attributed to Jean de Reyn was unmistakably due to the latter's greater reputation and to a misleading biographical reference in 1868. The Brussels portrait of a lady dated 1637 is the first work by Jan Pietersz. van Rijn to be found. It is stylisticallly consistent with the œuvre of a number of other Hague painters who worked for the local citizenry and whose pictures display the same sober and conservative character. In Thieme-Beckers' dictionary of artists, the only one of its kind to devote a separate paragraph to Jan van Rijn of The Hague, a monogrammed Portrait of a Man dated in 1636 appears. However, the whereabouts of the portrait, which was in a private Berlin collection in 1883, remains unknown to this day, so that the somewhat speculative attribution on the basis of the not completely distinct monogram cannot be verified. For the same reason it is no longer possible to determine whether a portrait of Jan Davidsz. de Heem that was auctioned in 1924 should now be attributed to Jan van Rijn or Jean de Reyn. In all respects the 1637 painting now attributed to Jan Pietersz van Rijn will undoubtedly be a help in finding other works by this Hague painter.