The filtration efficiencies of cellulose acetate charcoal filters for removal of such semi-volatile compounds as acetaldehyde, isoprene, acetone, benzene, and toluene were studied. Acetaldehyde deliveries on a per puff basis were determined for the charcoal filters, and the deliveries were remarkably increased after the 7th and 8th puffs in the case of charcoal filters. Cellulose acetate charcoal filters have a pronounced effect on filtration efficiencies for removing isoprene and acetone during initial puffs. These charcoal filters enhance the filtration efficiencies for removing benzene and toluene during all puffs except the last. The main conclusions from these results on semi-volatile components are as follows : (1) During the first few puffs, the adsorption of semi-volatile components will occur due to activated carbon. By using a large amount of charcoal, the adsorption of semi-volatile components increases remarkably. (2) During the last few puffs, the adsorbed semi-volatile components seem to desorb, especially when a small amount of charcoal is used. (3) The low boiling semi-volatile components such as acetone and acetaldehyde, which are adsorbed during the first few puffs, desorb readily during the last few puffs.