Pm6 in bread wheat (Triticum aestivan I.), which was transferred from Trition,timpopheevii L, is a gene confering resistance to the powdery midew disase casued by Erysiphe granints f. sp. Tritici, Six near-isogenie lines (XILS) of Pm6 in a cultivar Prins background were analyzed to map this gene using restriction fragment length polymorphism (RFFLP). Each of the six NILs posscssed a T. timophecvii-derived scgment, varying in length, and associated with powdery midex resistance, Lines IGVI-465 (FAO163h/7*Prins) and IGVI-467 DAED 59B/7*Prins) had the shortest introgressed scgmetns. whith weere delected only by DNA probes BCD 135 and PSR934. respectively. The polymorphic loci detected by both probes were mapped to the long and of chromosomc 2B. Lines IGVI-458 C (CII 259/8*Prins) contained the longest T. timopheevii segmets involving both arms of donor chromosome 2G aetoss the centromere, All these introgressed segments had an overlapping region flanked by the loci xpsr934 and xbed135 on 2BL Thus, Pm6 was located in this region since the powdery midew resistance in all the NILs resulted from the introgressed fragment, Lising the F, mapping population from a cross of IGVI-463 (PII70914/7*Prins, Pm6 was shown to be closely linked to the loci xbcd135 and xbed 266 at a genctic distance of 1.6cM and 4.8cM, respectively, BCD135 was sucessully used detecting teh presence of Pm6 in different genetic hackgrounds.