The connection between smoking behaviour (number of puffs, puff volume, depth of inhalation, duration of inhalation) and the increase in both nicotine and carboxyhaemoglobin (COHb) in venous blood was investigated with methods developed especially for measurement of the puff volume, the depth of inhalation, and the duration of inhalation in 28 inhaling cigarette smokers. A significant correlation could be demonstrated between the smoking parameters and the nicotine and carboxyhaemoglobin increase. The weighting obtained shows that the number of puffs is the most important parameter affecting the increase in nicotine, whereas the depth of inhalation and the puff volume are of much less relevance. The duration of inhalation does not affect the nicotine level. A significant increase in nicotine cannot be attained in non-inhalative smoking of cigarettes with an acid mainstream smoke (n = 14). The increase in COHb is most affected by the puff volume, and slightly less by the number of puffs and the depth of inhalation. The duration of inhalation does not affect the COHb level.