The beneficial effect of short-term smoking reduction in reducing lower respiratory tract inflammation was assessed in 15 healthy heavy smokers. All underwent fibreoptic bronchoscopy and bronchoalveolar lavage and were then treated with at least 20 mg of nicotine gum daily. Self-reported cigarette consumption decreased from 50.7 +/- 2.3 to 18.8 +/- 1.5 (p less than 0.001) cigarettes daily, and expired CO decreased from 48.5 +/- 2.5 to 27.3 +/- 2.5 ppm (p less than 0.001). After two months, repeat bronchoscopy and bronchoalveolar lavage revealed that bronchial inflammation, as assessed by direct inspection, neutrophilia of bronchial lavage fluid, and the number of alveolar macrophages, the number of alveolar neutrophils and the concentration of neutrophil elastase alpha 1-antiprotease complex in alveolar lavage fluid, had improved significantly. The present study suggests that smoking reduction may be associated with an improvement in lower respiratory tract inflammation in heavy smokers and may, if persistent, be an alternative for smokers who cannot, or do not wish, to quit.