Cadmium and lead were determined in the parts of a filter cigarette after fractional smoking. The partitioning of these elements into the main smoke stream, consisting of particulates and gases, also into the side stream, the ash and the butt was determined. Approximately 70% of the lead mobilized by the smoking process was found in the ash; about 50% of the cadmium was transferred into the side stream. The overall trend shows an increase in the amount of the metals in the main stream as the number of puffs is increased. A model for the behavior of the main stream components within the cigarette was developed and showed a high analogy with the Lambert-Beer law describing the absorption of light.