Background: Gingivitis is a common inflammatory condition. We explored the value of flow cytometry of saliva in patients with periodontal inflammation. Methods: A cohort of 249 healthy adults (age range: 18-81. y; 2.5th to 97.5th percentile: 19-66. y) was investigated for caries, dental plaque and gingivitis. Saliva was analyzed using flow cytometry on a Sysmex UF-1000i®. Results: Sysmex UF-1000i® is capable to reproduce reliable measurements of cellular components in saliva. A statistically significant lower number of salivary bacteria was found in patients with gingivitis in comparison with healthy adults (p<0.0001). A significant difference in salivary leukocyte count was found between patients with different gingival index scores (p<0.0005). The gingivitis score was strongly dependent on the number of salivary leukocytes, the age of the patient and the degree of caries and dental plaque (r2=0.60, p<0.001). At a cut-off level of 103 leukocytes/μl saliva, an area under the curve of 0.82 was obtained with a sensitivity of 76% and a specificity of 78% in patients (>35y) with a gingivitis score of 3. Conclusion: Flow cytometry is an alternative method to evaluate local inflammatory processes in the mouth with a sensitivity of 76% and a specificity of 78%. © 2014 Elsevier B.V.