This study was aimed to examine the association of periodontitis with white blood cell (WBC) count and blood pressure (BP). In 2002, 424 subjects (manufacturing workers) were investigated for periodontitis by a general dentist. All were Japanese. Among them, 364 subjects (269 men and 95 women) who also attended the next year's (2003) screening were enrolled for this study. Of the 364 subjects, 55 (15.1%) had periodontitis. We also measured the BP and WBC count in periodontitis and non-periodontitis subjects at baseline and 1-year later follow-up. The WBC count higher in subjects with periodontitis than in subjects without periodontitis, both at baseline [mean +/- standard error (SE) 6.6 x 10(3) +/- 0.2 x 10(3)/ml vs 5.8 +/- 0.3 x 10(3)/ml; p < 0.001] and follow-up (7.0 +/- 0.3(3)/ml vs 6.5 +/- 0.1(3)/ml; p = 0.003). The systolic BP was higher in subjects with periodontitis than in subjects without periodontitis, both at the baseline (128 +/- 2.1 mmHg vs 120.8 +/- 0.8 mmHg; p < 0.001) and follow-up (129.2 +/- 2.3 mmHg vs 123.0 +/- 0.8 mmHg; p = 0.011), and so was the diastolic BP both at baseline (76 +/- 1.5 mmHg vs 71.2 +/- 0.6 mmHg; p = 0.003) and follow-up (80.5 +/- 1.7 mmHg vs 75.4 +/- 0.7 mmHg; p = 0.004). Periodontitis is associated with increased BP and WBC count. This finding may provide one underlying pathway linking periodontitis and cardiovascular disease.