Modern agriculture and forestry are based on the use of large diesel-fuelled vehicles. The emissions from these vehicles cause substantial damage to the production area and to the surrounding environment. A useful method for analysis of the environmental load from a production chain or a process is LCA. The results from LCA analyses performed on food production show that an important part of the environmental load is caused by emissions from internal combustion engines. Very few data are available on discharge of emissions from agricultural tractors. Therefore, the data used in most LCA studies is from measurements on diesel-fuelled trucks or from large wheel loaders. There are many reasons to believe that these figures are not representative for tractors performing typical agricultural work operations. The shortage of data contributes to the possibility that LCA results describing environmental loads from modern food production may have very high error levels and high uncertainties. The report describes a study performed in order to quantify engine emissions from a medium size (70 kW) tractor when performing typical agricultural work operations. To obtain emission values specific for different driving operations, time series for the load at the engine are recorded when performing typical operations. These data are then combined with test bench emission data, in order to calculate the discharge of emissions for each of the recorded operations. The operations studied were ploughing, harrowing, stubble cultivation, sowing, loading and transporting. Emissions were calculated for two different diesel fuels and for RME. The general results are a) that the use of one single emission factor for all types of driving operations may result in very high error levels, and b) that the emission factors normally used in LCA studies can not be used for agricultural tractors. Important areas for further research are described and discussed in the last part of the report.