Warm season annual grasses are commonly used by dairy producers in their forage programs for grazing, green chop, hay, or silage production. Most warm season annual grasses require less water to grow and are more drought and heat tolerant than corn. These characteristics along with improved varieties that have improved DM yield and higher fiber digestibility have increased the interest in their use for dairy cattle. The incorporation of the brown-midrib 6 gene (bmr) in varieties increases in fiber digestibility and energy to support production compared with non-bmr varieties. Warm season annuals grasses are susceptible to nitrate toxicity during drought conditions. Prussic acid toxicity is an issue for members of the sorghum family during early growth and after stress from frost. Of the warm season annuals, forage sorghum is used more frequently for silage production. It is susceptible to lodging, but new brachytic dwarf varieties have shorter internodes, reducing lodging potential while providing forage with greater leaf to stem ratio. Diets based on bmr-6 forage sorghum silage have supported milk yield comparable to that of corn silage based rations when balanced for fiber content. Pearl millet silage support similar DMI and milk yield, and higher milk fat percent compared with corn silage; however, other trials reported reduced ADG or milk yield when fed to growing heifers or lactating cows. Differing responses may be partially attributed to differences in fermentation of the silages produced from pearl millet, which is more challenging to ensile if water-soluble carbohydrate concentrations are low. Data on bmr sorghum-sudangrass are limited and suggest that these forages can support solids-corrected milk yield similar to that of corn silage-based diets. Warm season annual grasses can be effectively incorporated into forage systems for dairy cattle. Improved varieties, especially bmr varieties, can support acceptable milk yield.