Legumes have a significant role in many farming systems of the tropics and subtropics through their contribution to enhanced nutritive value of the animal diet, biological nitrogen fixation and landscape stability (Humphreys, 1995). The great potential of legumes to increase productivity of livestock is being related with their high content of nutrients, especially protein and other nutrients often deficient in grass or low quality hay diets for ruminants. In Indonesia, legumes are often used for replacement of costly concentrate in ruminants diets. Norton and Poppi (1995) reported that quality of tropical legumes varies between and within species but is generally higher than that of tropical grasses. It is well known that the major factors limiting intake and digestibility are those associated with rate and extent of forage degradation by microbial and physical factors in the rumen, primarily the amount of cell wall constituents and the extent of lignification. Association of polysaccharides of cell wall with lignin hinders attack by microbial enzymes and prevents the physical attachment of bacteria to the cell wall. Menke et al. (1979) reported that the amount of gas released when a food is incubated in vitro in the rumen fluid, is also closely related to digestibility of the food and could be used to predict food intake. There is very little information available on the rumen degradation characteristics and in vitro gas production of the tropical legumes. Objectives of the present study were to assess differences in in vitro degradation and gas production between five commonly used legumes in south Sumatra, Indonesia.