The GeneChip Wheat Genome Array contains 61,127 probe sets representing 55,052 transcripts for all 42 chromosomes in the wheat genome. By providing comprehensive coverage of the wheat genome, the GeneChip Wheat Genome Array is an important tool for plant genetics and crop improvement. Sequence information for this array includes public content from Triticum aestivum UniGene Build 38 (April 24, 2004). Also included are ESTs from the wheat species T. monococcum, T. turgidum, and Aegilops tauschii, and GenBank full-length mRNAs from all species through May 18, 2004. The Wheat Genome Array was created within the Affymetrix GeneChip Consortia Program and provides scientists with a single array which can be used for gene expression studies in these wheat species.