This paper presents the initial results of an experimental investigation of regulated and unregulated emissions of a boiler fueled with biodiesel and heating oil. In particular CO, SO2, NOx, particulate matter (PM), Polycyclic Aromatic Hydrocarbons (PAH), Volatile Organic Compounds (VOC) and aldehydes emissions were examined. When using biodiesel, a strong reduction in CO and PM emissions was recorded with respect to home heating oil. The PAHs contained in the PM in the case of biodiesel were nearly 13 times less toxic than in the oil case: the formaldehyde, on the contrary, is nearly double for biodiesel. The VOCs were very low for both fuels. The results indicate there may be benefits to using biodiesel in home heating or in industrial processes. (C) 2008 Elsevier Ltd. All rights reserved.