A general overview of the utilization of the foliage of legume trees in animal production systems in tropical areas is presented. The experience of their utilization in mixed type of small farm agricultural systems is emphasized for the Central American region. Three species: Leucaena leucocephala (Lam.) de Wit, Erythrina sp., and Gliricidia sepium. are reviewed in terms of their establishment and utilization in association with grasses or as protein banks. Results of research conducted in Costa Rica and Guatemala under different ecological conditions are discussed in terms of dry matter production, forage quality, consumption by dairy cows and rumen degradation. The main advantages and disadvantages of the use of legume trees are discussed in relation to small farm agricultural systems.