Technical Abstract: The USDA-ARS National Plant Germplasm System (NPGS) provides both germplasm and data on genetic resources to researchers and breeders world wide. New tables and codes that hold data relating to molecular markers and multi-locus genotypes have been added to the Germplasm Resources Information Network (GRIN) database to augment the phenotypic and passport data that were already available for plant materials in the NPGS. The revised tables accommodate multiple marker classes, provide raw data for individuals, accept polyploid data, and provide a record of methods, standards, and control values. A long term goal is to make the GRIN molecular tables interoperable with other genomic databases. The development of this capacity provides critical data infrastructure for future genotype-phenotype association studies and gene discovery.