The association between smoking and loss of periodontal bone height was investigated in Swedish dental hygienists. The study group included 210 subjects: 24 to 60 years of age, 30% smokers, 32% former smokers, and 38% non-smokers. The study was based on bite-wing radiographs, where loss of the interproximal bone height was measured as the distance from the cemento-enamel junction (CEJ) to the interdental septum (IS). The magnitude of the CEJ-IS distance was read at 12 sites, representing 3 maxillary and 3 mandibular bone septa in each subject. The CEJ-IS distance was significantly greater for smokers when compared to non-smokers, mean +/- SEM 1.71 +/- 0.08 mm and 1.45 +/- 0.04 mm, respectively. The mean +/- SEM for former smokers was 1.55 +/- 0.05 mm. In smokers, the CEJ-IS distance increased with increased smoking exposure. The results, based on adults with good oral hygiene, suggest that loss of periodontal bone is related to smoking. The smoking related bone loss is not correlated with plaque infection.