ruzigrass ( Urochloa ruziziensis (r. Germain & Evrard) Crins, syn. Brachiaria ruziziensis Germain & Evrard) is a tropical forage native to Africa, first introduced in Brazil in the 1960s. r uzigrass is diploid, presents sexual reproduction, and is a model species for the generation of genomic resources in the Brachiaria genus. Brachiaria species are the most important livestock forage in the tropics, covering more than 70 million ha in Brazil alone. We have used multiplex panels of microsatellite markers to characterize the genetic diversity of ruzigrass germplasm collected in Africa, and of a local population collected in Bra - zil, to obtain information for its conservation and use in breeding programs. Fifteen SS - ers were used to Genotype 114 ruzigrass sam ples. Summary statistics, as well as estimates of F ST and partitioning of genetic diversity were obtained. Clustering and genetic structure analy - ses were performed. r esults showed high val- ues of heterozygosity in the African and Brazilian populations. Although African and Brazilian sam - ples formed distinct groups in clustering analy - ses, and Bayesian analysis of genetic structure distributed samples into three clusters, estimates of pairwise F ST values showed no differentiation between African and Brazilian groups of sam - ples. results indicated that the introduction of ruzigrass in Brazil did not cause a major decrease in genetic diversity. Brazilian local populations might harbor favorable alleles that will be useful for ongoing and future breeding programs. They offer great opportunities for ruzigrass germplasm collection and conservation of genetic diversity, before attempts to access germplasm in its cen - ter of diversity are undertaken. M. Pessoa-Filho, Embrapa Cerrados, P.O. Box 08223, Brasilia, DF, Brazil 73310-970; A.L.S. Azevedo, F.S. Sobrinho, Embrapa Dairy Cattle, Rua Eugenio do Nascimento, 610, Juiz de Fora, MG, Bra