Total nitrogen and nicotine contained in cigarette smoke condensate and condensate fractions have quantitatively been estimated. The results show that only 5 to 36 % of total nitrogen can be related to nicotine. It is tried to determine the balance of nitrogen in smoke condensate. The calculations made suggest that, for example within the group of nitrogenous compounds, there might be smoke constituents which are still unknown and which occur at relatively high concentrations.