A regression mapping approach to localize simultaneously two unlinked interactive QTL is proposed. It extends the simple ‘marker regression’ method of Kearsey and Hyne (1994) to the case of two linkage groups, each with a single QTL having no additive (main) effect, and acting only through epistasis (interaction between a pair of QTL). It allows the localization of the two QTL on the two linkage groups involved by a least square method, which is theoretically more precise than the classical study of interactions between pairs of markers. An application of the method to interactive QTL controlling plant height in bread wheat is presented. Further possible developments are briefly discussed.