The national olive collection at the United States Department of AgricultureAgricultural Research Service National Clonai Germplasm Repository, Davis, CA (NCGR-Davis) contains a number of accessions with uncertain origino In order to determine their genetic identification, a genotypic comparison was made with the Mediterranean cultivars of the Italian national collection at the Agricultural Research Counci! - Research Centre for Olive Growing and Olive Oi! Industry (CRA-OLI) and with data available at CNR - Institute of Plant Genetics (CNRIGV). This study was conducted using seven SSR (Simple Sequence Repeat) markers. At present, SSR markers represent the most useful molecular tools to characterize olive cultivars, because of their high polymorphism, uniform distribution across the genome, co-dominant inlIeritance and the availabiIity of a common set of loci with reference alleles. However, most SSR markers isolated from olive, with a di-nucIeotide repeated motif, can stilI easily lead to misinterpretations in allele assignment. SSR data produced from both collections were compared and standardized using previous reference data. Highly comparable molecular profiles were obtained. A preliminary identification of the NCGR olive collection is described herein.