The question, as to whether the milder cigarettes are safer is still controversial. According to some authors, smokers would compensate, at least partially, the lightening of smoke by modifying their smoking behaviour, notably by increasing their cigarette consumption. A survey of the literature show that the increased consumption is observed only in peculiar conditions, after switching to lighter cigarettes, imposed by experimenters. In such artificial conditions, one notice that the increasing of consumption is significant only after very short time and with great differences in cigarette yield. The consumption variations diminish with the time and are totally absent after spontaneous switching. In "steady state" smokers, who have never changed of product or did a long time ago, there is no difference in consumption according to the cigarette class. In France, on a large sample of population, we observed that the consumption tend, on the contrary, to be lower in light cigarette smokers. The changes of smoker behaviour sometimes attributed to the lightening of' cigarettes would be due to experimental conditions such as allocation of free cigarettes, very large decrease in tar and nicotine yield and time too short to get accustomed to the new products.