The addition of charcoal to cigarette filters has been reported to reduce concentrations of many volatile compounds found in cigarette smoke. The purpose of this investigation was to evaluate the effectiveness of charcoal addition on the yields of Hoffman analytes when cigarettes are smoked under multiple regimes. Seven Canadian products with charcoal filters (CFC), along with 3 acetate filter cigarettes (CAC), were evaluated under 6 smoking conditions; puff volume (25, 35, 45, 55mL), puff frequency (30, 50, 60 seconds), vent blocking (0,100%). Charcoal in the filters varied from 0.05 to 0.09mg/mm³. Tip ventilation, pressure drop and paper porosity were also measured in order to identify additional factors important in filter effectiveness. A comparison of slopes from the smoke constituent yield plotted against the total volume of smoke was used to assess effectiveness. As expected, deliveries of Hoffmann analytes increased as the total smoke volume increased for both CFC and CAC. For most of the volatiles examined, increased charcoal filter length and increased tip ventilation correlated with a lower concentration (yield/litre) and were found to be significant factors in filter effectiveness. In a comparison of CFC's versus CAC's, it was found that yields of most compounds by a popular CAC were either similar or slightly increased compared with the highest yielding CFC and largely independent of smoking condition. When the same CAC was compared with the lowest yielding CFC, the yield ratio for a number of compounds, pyridine and styrene in particular, was not independent of smoking regime. Under the 'lightest'smoking condition, the CAC delivered 10 times more pyridine than the comparator CFC decreasing to a factor of 2 under intensive smoking (no vent blocking).