Studies are described for the development of a combined diesel particulate and NOx emissions control system for underground diesel mine vehicles. It is known that methods for reduction of NOx tend to increase particulates unburned hydrocarbons and carbon monoxide emissions. The strategy pursued, therefore, is to attempt to find a compromise combination using exhaust gas recirculation (EGR), for NOx control, and a ceramic diesel particulate “wall” filter (DPF), together, to make significant reductions of both NOx and particulate with minimum increases in CO and hydrocarbon emissions.The application of Corning DPFs, of EGR, and of DPFs and EGR in combination are made on heavy duty diesel engines of a type typically used on load-haul-dump vehicles in mining operations. Steady state tests and simulated mine duty cycle tests are made using engine dynamometer facilities. The ability of the DPF's to auto-regenerate by burn-off of the collected particulate during regular engine operation is studied by evaluation of duty cycle exhaust temperature profiles and by simulated duty cycle runs.