Mungbean seeds are often attacked by bruchid insects causing serious damage to the grain during storage. The susceptible/resistant characteristics of mungbean against bruchids have been investigated at the protein level. Seeds of the susceptible cultivar Osaka-ryokuto and the resistant near-isogenic line BC20 were collected at 5, 9, 13, 17, 21 and 23 days after flowering. Crude, cytosol and membrane protein fractions were extracted from the seeds for twodimensional polyacrylamide gel electrophoresis analysis. In Osaka-ryokuto six proteins were found in higher amounts compared to BC20 in the crude protein extract. Some of these proteins were homologous to legumin B and liguleless1. And in BC20 one unique protein, homologous to SalF1R, was identified. In the subcellular protein fractions, nine unique proteins were identified in BC20, seven in the cytosol and two in the membrane fractions. These proteins were homologous to chitinase, alanine aminotransferase in membrane, and SalF1R, β-1,3- glucanase, protein phosphatase 2A, peroxidase BP 2A, provicilin and canavalin in the cytosol fractions. Previous findings of many researchers reveal that these are mainly defence-related proteins. Thus, it is suggested that the above proteins may play a role in maintaining the resistance of line BC20.