ABSTRACT. Cyperus rotundus plants showing symptoms of root knot were observed in the municipality of Santa Maria, Rio Grande do Sul state, Brazil. Based on the morphological, esterase phenotypes and molecular analyses of rDNA-ITS and D2-D3 regions of 28S rDNA, the causal agents of the observed symptoms were identified as Meloidogyne graminicola, pathogenicity was confirmed by fulfilling Koch?s postulates. To our knowledge, this is the first report of M. graminicola in C. rotundus in Rio Grande do Sul State, Brazil. © 2019, Australasian Plant Pathology Society Inc.