Gluten strength is an important end-use quality factor in durum wheat (Triticum turgidum L. ssp. durum (Desf.) Husn.). The gluten index has become widely-used for selection in durum breeding programs because of its simplicity and independence from protein concentration. Our unpublished results indicate that gluten index is complexly inherited, so marker-assisted selection could be a useful tool in the development of cultivars with desired gluten strength properties. Genome-wide association mapping is one way to identify genomic regions for more detailed investigation. A sample of 81 diverse durum accessions collected from a variety of geographic origins was grown in replicated field trials at two locations for two years. Gluten index was determined on semolina, and the populations were genotyped with SSR markers. Using sub-population assignments as covariates, significant (P<0.05) marker-trait associations for gluten index were detected on chromosomes 2A, 2B, 3B, 4A, 5B and 6B in three or four of the tested environments. The 2B region near Xgwm429 was highly significant (P<0.0001) in all four environments, and explained the majority of phenotypic variation for GI (20%-27%). Regions on 3A and 4A also showed strong associations. The regions identified on 2A, 5B and 6B confirm earlier reports of gluten index QTL on those chromosomes and validates the usefulness of association mapping to identify marker-trait associations in durum wheat. To our knowledge, this is the first report of a marker associated with gluten index on chromosome 2B, and this and the other identified regions will be further studied in bi-parental mapping populations.