This paper presents a literature review of published scientific studies of the effects of tobacco product ingredients and various experimental additives on cigarette smoke composition and its biological activity. The format of this work is that of an uncommented reference paper rather than a critical scientific review. Therefore, the mention of an ingredient in this survey does not imply that it is used by the tobacco industry or that it is covered by any existing national regulations. A broad range of scientific papers and patents on tobacco ingredients is included as well as studies on experimental ingredients. This review may provide public health officials as well as scientists in government agencies and in the tobacco industry with a helpful overview of published information on tobacco product ingredients, their transfer into mainstream cigarette smoke, pyrolysis products, and influence on the biological activity of mainstream cigarette smoke.