Chromosome numbers and ploidy levels of 24 accessions of 17 species of tribe Panicoideae from Argentina, Cuba, and Brazil are given. Most of the studied species are endemics. The studied taxa are: Axonopus aureus P. Beauv., Dichanthelium aequivaginatum (Swallen) Zuloaga, D. stipiflorum (Renvoize) Zuloaga, D. surrectum (Chase ex Zuloaga & Morrone) Zuloaga, Homolepis isocalycia (G. Mey.) Chase, Paspalum arenarium Schrad., P. blodgettii Chapm., P. capillifolium Nash, P. coryphaeum Trin., P. distortum Chase, P. durifolium Mez, P. lindenianum A. Rich., P. oligostachyum Salzm. ex Steud., P. pumilum Nees, P. scutatum Nees ex Trin., P. strigosum Döll ex Chase, and Plagiantha tenella Renvoize; of these, the chromosome numbers of D. aequivaginatum, D. stipiflorum, D. surrectum (n = 9), Homolepis isocalycia (n = 20), Paspalum capillifolium, P. distortum, P. lindenianum, P. oligostachyum, and P. strigosum (n = 10) are presented for the first time. A new diploid cytotype (n = 10) for Paspalum blodgettii was found.