Field expe1iments were conducted to determine the effects of applied nitrogen (N) on dry matter (DM) yields of sorghum-Sudan grass (Sorghum bicolor [L.] Moench) cultivars and millet (Pennisetum typhoides [Burm.] Stapf and Hubbard) at three locations, Jaguari, Santa Maria, and Sao Vicente in the state of Rio Grande do Sul, Brazil. The adaptation of these grasses and their susceptibility to leaf disease caused by Helminthosporium turcicum were also evaluated. Six sorghum- Sudan grass cultivars, 'Beef Builder', 'NK 300', 'NK 325'. 'Pioneer 931', 'Pioneer 988', 'Sordan NK 67', and millet were studied at each location during 1972 and 1973. Fertilizer treatments consisted of three N levels (0, 75 and 150kg/ha) applied annually in split applications. Grass DM yields were almost doubled using high rates. The most efficient N utilization occurred with 75kg/ha of N annually. Millet was better adapted than sorghum- Sudan grass to the climatic and edaphic condition at Jaguari. Sorghum Sudan grass cultivars gave the highest yields at Santa Maria and Sao Vicente indicating that they were we1l adapted to those two areas. Millet was highly resistant to Helminthosporium turcicum. All sorghum-Sudan grass cultivars were infected to some degree with this disease and 'NK 325' appeared to be the least susceptible. The results of this study demonstrate that DM yields of Sorghum- Sudan grass cultivars and millet can be significantly increased with fertilizer provided other plant nutrients and moisture are readily available in the soil. In areas of Rio Grande do Sul with a high incidence of Helminthosporium turcicum or on soil subject to frequent moisture stress, millet appears to be better adapted than sorghum- Sudan grass. All the cultivars studied are capable of producing large quantities of forage for grazing or soilage in Rio Grande do Sul Brazil.