Passive exposure to cigarette smoke has emerged as a significant risk factor in the development of asthma and allergic airways disease. The pathogenetic mechanisms are not known, but increased absorption across the airway epithelial lining has been suggested as one possible mechanism of this effect of cigarette smoke. This study examines the absorption-permeability of the nasal epithelial lining in cigarette smokers and non-smokers. For comparison, the effect of a detergent, dioctylsodium sulfosuccinate (DS), is also examined. A solution containing 51Cr-EDTA (51-chromium labeled ethylene diamine tetraacetic acid) (mol. wt. 372 Da) was instilled and maintained in the nasal cavity in six smokers and 12 non-smokers for 15 min. Urine was collected for 24 h after the instillation. The accumulated amount of excreted 51Cr-EDTA was measured and expressed as millilitre nasal instillate. In six non-smokers the procedure was repeated when DS has been added to the instillate. The median recovered amount of 51Cr-EDTA in smokers 0.07 ml (range 0.04-0.32) was not significantly different from that in non-smokers 0.16 ml (0.01-1.22). The recovered amount of 51Cr-EDTA increased from a median of 0.18 ml (0.01-1.22) to 1.13 ml (0.53-1.80) after addition of the detergent (P = 0.028). We conclude that the nasal airway absorption-permeability is not increased in smokers. Hence, passive exposure to cigarette smoke may not produce an impairment of airway barrier functions.