Grass cultivars Mulato (a hybrid; Brachiaria brizantha χ B. ruziziensis), MarandCi (Β. brizantha) and Toledo (B. brizantha) are the most important tropical grass releases in Latin America for grazing. However, information on yield and persistence of these cultivars in Puerto Rico is limited. This study assessed yield, nutritive value and mob grazing effects of Mulato, MarandCi and Toledo. The study was conducted at the Corozal substation of the Agricultural Experiment Station of the University of Puerto Rico. Soil type was of the Corozal series (fine clay, mixed, isohypetermic Aquic Haplohumults). Established stands of Mulato, MarandCi and Mulato were stocked every 35 d with yearling steers (mob grazed for 1 to 2 d to a 15-cm height). Prior to grazing, a 1 m2 quadrant was clipped, weighed and dried to determine yield, and sub samples (500 g; four samples in the year) were ground to determine their chemical composition [crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF)]. All pastures were mob grazed for 15 grazing cycles to determine changes in yield over time. Mean yield of Mulato (1,207 kg/ha), MarandCi (1,094 kg/ha) and Toledo (1,271 kg/ha) were different (P<0.05), but there were no differences in CP (6.8%). There was a cultivar effect (P<0.05) on NDF and ADF, with a lower NDF (64.6%) and ADF 33.6%) for Mulato. There was a grazing cycle date effect on yield (P<0.05) consistent with rainfall patterns in the Corozal area. After 1.5 years of grazing it is evident that all three cultivars persisted, but that grazing management is needed (longer periods of regrowth) during the dry periods