The compatibility of two tropical grasses (Brachiaria humidicola (Bh) and Panicum maximum (Pm)) and three legumes (Arachis pintoi (Ap), Stylosanthes capitata (Sc) and Stylosanthes guianensis (Sg)) were examined at two fertilizer application levels in a tropical South American savanna region. Pairs consisting of one grass and one legume were planted on a reclaimed Colombian lowland. Changes in biomass over time, growth patterns, and the relative palatability of these species indicated by grazing preference were measured. Among the two grass species, Bh showed strong growth, even under the low fertility condition, while Pm required the high fertilizer application level for establishment and growth. Among the legumes, Sg grew vigorously, even at the low fertility level, and could compete with Bh in biomass production. Sc was less vigorous than Sg, but was preferred by cattle. The growth habit of Ap was stoloniferous and it required a long time period to make a dense sward, because its seeding rate was low due to the bigger seed size. Among the three legume species, Ap was most preferred by cattle, and Sg was the least, but was nevertheless eaten by cattle if no other legumes were present. Considering the compatibility of these grasses and legumes, the mixture of Sg and Bh produced a higher level of herbage biomass than the other grass-legume mixtures examined in this study. The Ap and Pm mixture also had good compatibility, and its palatability to cows was higher than the other mixtures.