Technical analysis of the Mellon and Kahn Madonnas shows that they are not the products of a single artist. Discusses the similarities (construction of support, lack of underdrawing, limited palette) and differences (outlining of figures, sequence of painting, choice of pigments), and suggests that, at one time, the Kahn Madonna may have been used as a model for therestoration of the severely damaged Mellon Madonna. (Abstractor's note: This article is a complement to Hans Belting's art historical study of the Mellon and Kahn Madonnas in the National Gallery, Washington, D.C. ( The Byzantine' Madonnas. New facts about their Italian origin and some observations on Duccio, Studies in the History of Art, 12, PP. 7-22)) R.A.R. -- AATA