Fifteen subjects participated in a randomised, placebo-controlled cross-over study to assess the effect of a nicotine vapour inhaler on craving and other withdrawal symptoms during a two-day smoking-free period. Craving and withdrawal symptoms were rated nine times over the two-day period on 10 cm visual analogue scales. Plasma nicotine concentrations in the afternoon of each study day were determined. The results show that active treatment was significantly superior to placebo in decreasing craving and other withdrawal symptom scores. No difference was found between two inhalation techniques, one with shallow, frequent inhalations (buccal technique), and the other with deep inhalations (pulmonary technique). The average number of active nicotine vapour inhalers and placebo inhalers used during the two-day sessions was 12 and 11, respectively. Afternoon plasma nicotine levels of approximately 7 ng/ml were obtained with both inhalation techniques. A strong correlation was found between the afternoon plasma nicotine levels and craving, a high nicotine level being associated with a low craving score. The study has provided information about how to use the nicotine vapour inhaler that could have important implications if it were to be approved for the treatment of tobacco dependence. The use of withdrawal symptom reduction as a surrogate end-point is discussed.