The ability of various potentiel indicators to predict soil N mineralisation in field conditions was tested on 53 unfertilised arable crop fields distributed all over France. In situ N mineralisation was determined with a calculation model using frequent measurements of soil mineral N and water content. On the ploughed layer (0-30 depth), soil organic C (SOC) and N (SON), microbial biomass C, light (>50 um) and heavy (<5O um) organic matter fractions and labile organic carbon or nitrogen (LOC or LON), obtained by autoclaving or tetraborate extraction, were measured. LON extracted by autoclaving showed the best correlatio with in situ N mineralisation (R2 = 0.47), followed by LOC extracted by autoclaving(r2 = 0.46), SON (R2 = 0.43) and SOC (R2 = 0.35). A multiple linear regression model including the selected variables LON, light C and labile organic matter C/N ratio explained 53% of in situ N rmineralisation without bias. However these indicators were not sufficient and a better prediction of in situ N mineralisation required other soil and cropping system information.