Reid, L. M., Xiang, K., Zhu, X., Baum, B. R. and Molnar, S. J. 2011. Genetic diversity analysis of 119 Canadian maize inbred lines based on pedigree and simple sequence repeat markers. Can. J. Plant Sci. 91: 651-661. Since the early 1920s Agriculture and Agri-Food Canada (AAFC) has been developing maize varieties and inbred lines adapted to the early maize growing regions. These inbreds represent a large group of genetically diverse genotypes; however, many of the inbreds are of unknown heterotic backgrounds. The purpose of this study was to classify 119 elite maize inbred lines released from AAFC into heterotic groups using both pedigree data and simple sequence repeat (SSR) markers and also to explore the consistency among different classification analyses. Pedigree analysis placed the inbred lines into eight groups, six of which corresponded to known major heterotic groups representing Iowa Stiff Stalk Synthetic (BSSS), European flint, Lancaster, Minnesota 13, Early Butler, and Iodent; the two remaining groups consisted of germplasm derived mostly from Pioneer 3990 or Pioneer 3994 sources. Simple sequence repeat analysis of 105 loci resulted in a clustering of the inbreds into 10 groups. In comparison with the grouping based on pedigree, the SSR clustering groups had some discrepancies and groups of genetically similar germplasm, based on pedigree, could not always be confirmed with molecular markers. The results of this study will allow researchers and maize breeders to make more informed decisions on the use of these inbreds in breeding programs.