The authors studied the influence of tobacco moisture content on yield and composition of total particulate matter as well as on the temperature in the combustion zone of plain cigarettes. Total particulate matter and single components of the smoke can best be correlated with the dry weight of tobacco burnt in the mainstream. These figures are estimated by semi quantitative measures. The yield of dry total particulate matter is independent of tobacco moisture content if calculated on the basis mentioned above. The nicotine content of the smoke decreases with increasing moisture content of tobacco. Calculations on the where about of total nicotine suggest that nicotine is increasingly decomposed in the presence of moisture. The yield of 1,2- and 3,4-benzopyrene rises with increasing moisture content but with different slopes. The temperature of the combustion zone is independent of tobacco moisture content. The chemical and catalytic importance of moisture in smoking processes is mentioned.