OBJECTIVE: To assess the effect of the various nicotine replacement therapies (NRT) on smoking reduction. DESIGN: During an initial sampling week, the subjects familiarised themselves with nicotine gum, patch, nasal spray, vaporiser (vapour inhaler) and sublingual tablet. A crossover design was used during the next four study weeks; during two of these weeks the subjects could select one nicotine replacement product of their choice to use, whereas during the other two they were randomly assigned a product to use. SUBJECTS: 143 men and women smoking an average of 22.6 (SD 7.0) cigarettes per day and exhibiting a Fagerstrom Tolerance Questionnaire (FTQ) score of 7.0 (SD 1.9). INTERVENTIONS: Subjects were asked to use as much NRT as they wished, yet to smoke enough to feel comfortable. MAIN OUTCOME MEASURES: Self- reported cigarette consumption, exhaled carbon monoxide (CO), withdrawal symptom score, cotinine plasma levels and motivation to quit were monitored over a period of five weeks. RESULTS: Self-reported smoking declined steadily over the five weeks, from 22.6 (SD 7.0) to 10.4 (SD 1.0) (P<0.001) cigarettes daily (54% decrease), with the biggest drop (37%) during the first product-sampling week. Smoking reduction was greater on average during the weeks when the subjects could choose their nicotine product than when products were assigned. CO readings decreased from 22.7 (SD 8.5) to 14.8 (SD 8.4) ppm (P<0.001) confirming a reduction in smoking (35% decrease), although cotinine levels remained steady, suggesting that subjects were titrating nicotine to their original levels. Withdrawal scores decreased over time (32% decrease, P<0.001), showing that there was no discomfort associated with the smoking reduction, and motivation to quit was enhanced by the treatment in most subjects (93%). CONCLUSIONS: NRT for aiding smoking reduction appeared to be safe, was associated with a clinically significant reduction in smoke exposure over a five-week follow up, and increased motivation to stop smoking. A smoking reduction procedure may help the very recalcitrant smoker gain confidence and increase the control over his/her smoking behaviour. More controlled research is needed to follow up these promising results.