There is a need for direct tailpipe sampling of diesel vehicles in mines in order to determine the effects of an emissions-based maintenance program, evaluate control technologies such as diesel particulate filters and identify the worst diesel particulate matter (DPM) emitters in a fleet of vehicles. Therefore, this study examined the performance of three portable instruments: a personal dust monitor (PDM) manufactured by Thermo Scientific, a prototype elemental carbon monitor (Airtec) manufactured by FUR and a prototype AE91 instrument from Magee Scientific. These instruments were evaluated on the basis of their ability to provide direct reading tailpipe analysis for DPM. It was determined that the average bias of the tailpipe results from the PDM and the Airtec were 3+/-12% and 4+/-20%, respectively, when compared to the standard method of determining tailpipe particulate concentrations from a diluted exhaust. It was also determined that the AE91 instrument correlated with the standard method.