By the late 1970s, eight technologies in the design of a "less hazardous" cigarette were classified as significant. The eight included: The tobacco blend, the filter tip, filter-tip additives, reconstituted tobacco sheet, paper additives, air dilution via paper porosity, expanded tobacco, and air dilution via filter-tip perforation. In addition to these eight cigarette-design technologies was another proposed technology which involved the incorporation of a substitute for some or all of the tobacco in the cigarette filler. Despite considerable research and development (R&D) effort on various tobacco substitutes that indicated the replacements in most instances fulfilled the definition of a "less hazardous" cigarette with regard to the chemical and biological properties of their mainstream smoke, tobacco substitute-containing cigarettes failed to attain consumer acceptability. As a result, several marketed products containing tobacco substitutes had an extremely brief tenure in the marketplace. Outlined herein is a summary of some detailed research conducted on the composition of the mainstream smokes from cigarettes containing either all-substitute filler or fillers comprising various substitute and tobacco mixtures as well as an all-tobacco cigarette.