We previously published results indicating that under natural conditions, smokers of superlight cigarettes produced on average less tar and nicotine than smokers of full flavour cigarettes, even if the ratio between the two groups was lower than predicted by the ratio observed after mechanical smoking (CORESTA 2001). This study confirmed previous results obtained in our laboratory, indicating that smokers of full flavour brands produced on average 12 mg tar and 0.9 mg nicotine from their usual cigarette under natural conditions of smoking (CORESTA 2000). These yields were concordant with the yields obtained by ISO or FTC mechanical smoking. The aim of the present study was to assess the yields obtained by another group of usual smokers of a full flavour brand of the French market (FF : 12 mg tar, 0.9 mg nicotine), and to compare them to the yields obtained by a group of 30 usual smokers of the corresponding light commercial brand (L : 8 mg tar, 0.6 mg nicotine). We collected 5 butts from each of the 60 smokers to assess the tar and nicotine yields obtained under natural conditions. Surprisingly, we here found that usual smokers of the FF cigarette produced higher yields than ISO/FTC ones (on average, 17.3 mg tar and 1.48 mg nicotine) ; moreover, the yields obtained by the usual smokers of the L cigarette were not significantly different from the yields obtained by the FF group. Nevertheless, one other study, performed in parallel and also published in this CORESTA congress, clearly demonstrates a decrease in total smoke exposure when usual smokers of a full flavour brand volunteered to switch to the corresponding light brand. These contradictory results will be discussed. The importance of knowing more about the smoking history of each subject than only the usual cigarette smoked will be emphasized.