Multiple-point linkage studies between genetic markers and between genetic markers and chromosomal interchanges provided information on gene order, centromere position, orientation of the linkage map, and location of interchange breakpoints on barley chromosomes 2 and 3. The estimated average amount of recombination recovered in the interstitial segment of interchange heterozygotes was only 4.3% of that normally expected. Using the patterns of reduction in recombination, the break positions of four 3-7, seven 2-3 and two 2-7 interchanges were estimated. The highest recombination value between the gene zb and four 3-7 and five 2-3 interchanges was .031. This places zb at or near the centromere in chromosome 3, since the break to zb interval is in the interstitial segment regardless of the breakage position. In these same interchange heterozygotes, the als-zb recombination values varied from .043 to .500. The one showing the greatest reduction was T3-7c, placing its break in 3 at or distal to the als locus. For T3 -7b there was no marked reduction in any of the intervals tested. This places its break point in 3 at or near the centromere. The use of multiple-point linkage tests is a reliable method of esti -mating centromere and interchange breakpoint locations on the linkage maps of barley.