This is a study of the similarities and differences between real and sham smoking; 15 participants, all of whom had a smoking history of more than two years, attended on two occasions within a balanced design. They were instructed to either smoke or sham smoke their own brand of cigarette as normally as possible. Real and sham smoking were highly correlated for various measures: frequency of puffs, puff duration, interpuff interval, puff volume, and puff pressure. This showed that the pattern of smoking was common across the two conditions. At the same time, there were differences between the two conditions in the intensity of smoking, such that sham smoking led to significant increases in puff duration, volume, frequency, and decreases in the length of interpuff interval. Sham smoking is often used in smoking experimentation as a control for various aspects of smoking. This is the first study to examine the commonalities between real and sham smoking in a detailed and systematic fashion.