Our objective was to compare potential C and N mineralisation of root and shoot residues for a wide range of grain legume species. Shoot and root residues from ten grain legume crops were collected either from a field experiment or from an outside pot experiment. Residues were incubated in soil for 112 days at 28°C under non-limiting N conditions. Biochemical characteristics of residues were determined and related to C and N residue mineralisation. Root and shoot residues decomposed rapidly after their incorporation into the soil. After 112 days of incubation, 41.8 to 71.5% of shoots-C and 33.5 to 57.9% of roots-C was mineralised. Most residues induced net N immobilisation at the beginning of incubation, while net N mineralisation occurred later during the incubation period. At the end of incubation -19.6 to 7.8% of shoots-N and -21.7 to 23.0% of roots-N was mineralised. The differences between shoots and roots residues decomposition and N mineralisation were explained by their biochemical characteristics, roots having higher N and lignin content and shoots higher soluble compounds contents, for all species. Differences between legume species in shoot and root N mineralisation were first explained by their C:N ratio and to a lesser extent by the lignin:N ratio and some biochemical fractions (i.e. cellulose, soluble compounds). Finally, these results can be used to parameterize decomposition models and help to predict C and N behaviour of the ten legume crop residues in soil