The increased use of diesel driven vehicles for all categories of commercial automobiles and even for private cars is the major trend observed worldwide over the last two decades in the transportation field. Although, cleaner than gasoline engines from the standpoint of view of carbon monoxide (CO) and hydrocarbons (HCs), diesel engines produce more aldehydes, sulfur oxides, and nitrogen oxides. Smoke and odor emissions are also a problem of great concern, most importantly, however, uncontrolled diesel engines emit significant amounts of particulate. These particulate emissions are a direct health concern as well as a serious source of overall environmental degradation. This paper discusses the diesel engine’s particulate emission control in detail.