Maize genetic resources program has three pillars, namely germplasm accessions management, in-situ biodiversity conservation, and prebreeding. Germplasm accessions management includes specific cooperative project ofregeneration of the Latin American maize landrace accessions, and evaluation and curatorial of the CIMMYT bank accessions. In-situ-biodiversity conservation entails the collecting and evaluation, and enhancement of specific landraces that are grown by the farmers in the context with their growing environment and cultural heritage in Mexico. Prebreeding is to develop and improve CIMMYT gene pools with incorporation of appropriate germplasm sources that are adapted in tropical, subtropical, and highland environment. For in-situ biodiversity conservation we evaluated new collections of Mexican race Zapalote Chico with our Mexican collaborators. Evaluations of additional Tuxpefio race and Brazilian races of Cateto and its subraces were conducted for development of core subsets. Formation and evaluation of breeding crosses of elite accessions were initiated or advanced in GEM type germplasm enhancement. In prebreeding topcross evaluations of a few tropical early pools, progeny formation of S 1 or S2, and development of donor sources were made mostly for yellow gene pools. Bank management and accessions introduction through the collaborative project with Latin American countries resulted in the total number of accessions that amounted to 20,863 as of September 2000. We made the seed shipment from Bank in the seed packets of 5,248 during the year.