Biodiesels are promoted as alternative fuels due to their potential to reduce dependency on fossil fuels and carbon emissions. Research in this field has focused on the study of the emissions of light duty vehicles. However, particle matter and gaseous emissions emitted from heavy-duty diesel engines fueled by Jatropha Oil Biodiesel (JOB) and Ultra-Low Sulphur Diesel (ULSD) has not been studied. The objective of this study is to explore the performance and emission levels of a Cummins 4-stroke, 4.8 liter, 4-cylinder diesel engine with common rail fuel injection, equipped with a cooled Exhaust Gas Recirculation (EGR). There was a substantial reduction by the use of JOB in unburned hydrocarbons (- 45%), carbon monoxide (- 75%), and particulate matter (- 25%) compared to emission from diesel fuel. At mid and high loads, NOx emissions were higher for JOB compared to ULSD. Most of the particles (64%) for ULSD were in a range of between 40 and 560 nm. On the other hand, most of the particles (94%) for JCB mode were between 6 and 40 nm.
 In the range between 6 and 40 nm, mass mean diameters in ULSD were 34.4, 34.7 and 33.3 nm while for JOB they were 21.3, 18.2 and 20.1 nm for 100, 50 for a 10% load, respectively.