Near-isogenic lines (NILs) and their recurrent parent Chancellor (Co) were used to identify restriction fragment length polymorphic markers linked to powdery mildew (Blumeria graminis (DC.) E.O. Speer f.sp. tritici) resistance genes Pm], Pro2, Pro3, and Pro4 in wheat (Triticum aestivum L. em. Theli). By mapping these poIymorphic markers in F: progenies from crosses of the NILs with C, it was found that Pro1 cosegregated with a polymovphic locus detected by DNA probe CDO347; Pro2 was linked to a locus detected by probe B CD[871 with a distance of 35 cM; Pm3b was linked to a locus detected by probe BCD1434 with a distance of 1.3 cM; Pm4a cosegregated with Xbcd1231-2A(2) and Xcdod78-2A, and was closeIy flanked by Xbcd1231-2A(t) and Xbcd292-2A both wiEh a distance of 1.5 cM. Aneuploid mapping of these markers indicated that locus Xcdo347-TA is on 7AL, Xbcd187]-5D on 5DS, Xbcd1434-1A on IAS, and loci Xbcd292-2A and Xcdo678-2A are on 2AL. The same polymorphic fragments detected in the Pm3b NIL by Xbcd1434-1A were found in Pm2a NIL. using several enzyme digestions.