Experiments were conducted on a 4-cylinder direct-injection diesel engine using ultralow sulfur diesel blended with ethanol, biodiesel and diglyme to investigate the particulate emissions of the engine under five engine loads at the engine speed of 1800 rpm. Four diesel-ethanol blends with oxygen concentrations of 2%, 4%, 6% and 8%, five diesel-biodiesel blends and five diesel-diglyme blends with oxygen concentrations of 2%, 4%, 6%, 8% and 10% were studied. Results show that the particulate matter (PM) emission decreases with the increase of oxygenate content in the blends. Ethanol addition into diesel fuel increases HC, CO, NOx and NO2 emissions and decreases particle number concentration. Diglyme addition into diesel gives an opposite trend to that of ethanol. Emissions of diesel-biodiesel lay between dieselethanol and diesel-diglyme. Under the same oxygen content, different oxygenates show different influence on emissions, particularly on PM reduction efficiency, indicating that the physical properties and chemical structure also influence the PM emissions. Diglyme addition into diesel fuel can simultaneously decrease PM and NOx emissions. (C) 2011 Elsevier Ltd. All rights reserved.