Technical Abstract: Synthetic hexaploid wheat (SHW), derived from tetraploid wheat ' Aegilops tauschii hybrid, is an excellent source of resistance genes for various diseases and insects in wheat. The objectives of this study were to evaluate the elite SHW lines developed at the International Maize and Wheat Improvement Center for resistance to Hessian fly and to predict the resistance genes in the resistant lines. A total of 118 elite SHW lines and 35 durum wheat parents were evaluated for resistance to Hessian fly biotype Great Plains (GP). The evaluation results showed that 52 SHW lines were highly or moderately resistant to Hessian fly while all the durum parents were susceptible, suggesting that the resistance genes were derived from A. tauschii D genome. The 52 SHW lines were haplotyped using eight PCR-based markers closely-linked with five Hessian fly resistance genes (H13, H22, H23, H26, and H32) previously identified in A. tauschii. Haplotype analysis revealed that 33 of the 52 resistant SHW lines have the same haplotypes as those of the five resistance sources. The other 19 lines have different haplotypes from those of the resistance sources, suggesting that these lines may not contain one of these five mapped resistance genes. Some of them might contain novel Hessian fly resistance genes. The resistant SHW lines identified in this study should be useful for the development of resistant cultivars and for genetic and evolutionary studies of resistance genes.