Objectives: To investigate whether the levels of serum C-reactive protein (CRP), salivary interleukin (IL)-6 and IL-lβ in metabolic syndrome (MS) patients can be potential monitors for inflammation in MS patients with severe periodontitis. Methods: A total of 114 MS patients and 49 systemically healthy subjects were enrolled. CRP in serum and IL-1β and IL-6 in non-stimulated whole saliva were collected from these patients and subjects and analysed by enzyme-linked immunosorbent assay (ELISA). Dental examinations were performed and the participants completed a questionnaire. Results: The serum CRP level of MS patients was higher than that of systemically healthy subjects, and increased as the number of components increased (P 0.05). No difference was observed in the salivary level of IL-6 and IL-1β between MS patients and controls or between MS patients with different components. The level of salivary IL-6 in MS patients with moderate/severe periodontitis was significantly higher than in MS patients with good periodontal health/mild periodontitis (P 0.05). After adjustment for age, sex and smoking habits, multivariate analysis showed that the corresponding odds ratio (OR) for MS combined with moderate/severe periodontitis was 1.21 (95% confidence interval [CI] 1.04–1.39, P = 0.012) for subjects with high serum CRP and salivary IL-6 and IL-1β were not risk indicators for MS combined with moderate/severe periodontitis. Conclusions: MS patients might be burdened by high levels of serum CRP. Serum CRP could be a potentially valuable biomarker to detect inflammation in MS patients with severe periodontal disease. Keywords: cytokines, inflammation, metabolic syndrome, periodontitis