Recent low tar, low nicotine cigarettes are fitted with high efficiency filters, or even filters with advanced technology. Some are designed and fabricated to vary or adjust the flow pattern of mainstream smoke. In the case of ventilated filters smoke passes mostly through the center with the air entering through the periphery. Taking such differences into consideration, the knowledge of cross-sectional smoke distribution in filters can be of great help in understanding of the efficiency and performance of smoke filtration. In this study a special devised attachment is used for dividing delivered smoke into concentric fractions and collecting each fraction separately onto Cambridge filters. The cross-sectional smoke distribution is then investigated based on the quantitative analysis of nicotine in each fraction. Smoke distribution curves on ventilated filters measured by this method are discussed here, showing the apparent changes of distribution in response to the degree of ventilation. As a result this study emphasizes the importance of cross-sectional distribution analysis in the evaluation of filters.