Metabolic syndrome (MS) and "low grade" systemic inflammation (LGSI) are very common findings in the older population. Although MS and LGSI have been associated in adults, it is not known what is the real contribution of MS, and its single components, to LGSI in older persons, due to the potential confounding effect of comorbidity and aging. We investigated the relationship between increased C-reactive protein (CRP) plasma levels, a marker of LGSI, and MS in 1044 older (> or =65 years) community dwelling Italian individuals enrolled the InChianti study. Metabolic syndrome was defined by the NCEP-ATP III-AHA/NHLBI criteria. High sensitivity CRP (hs.CRP) levels were measured by enzyme-linked immunosorbent assay, and defined as high when >3mg/L. The overall prevalence of MS was 31%. The prevalence of high hs.CRP was 54.5% in subjects with, and 41.3% in those without MS (p<0.001). MS was associated with high hs.CRP levels after adjustment for age, gender, and comorbidity (OR: 1.93, 95% CI: 1.46-2.55). Compared to subjects with MS and no LGSI, individuals with MS and LGSI were characterized by higher waist circumference, BMI, and HOMA score. Multivariate logistic regression analysis confirmed the association between waist circumference and high hs.CRP levels in subjects with MS (waist circumference III vs. I tertile OR: 2.60, 95% CI: 1.79-3.77) independent of age, gender, and important confounding variables including comorbidity. Additional analyses, conducted with and without dichotomization of hs.CRP levels, confirmed the central role of waist circumference in the LGSI phenomenon, independent of gender and diagnosis of MS. We conclude that in older individuals, MS is associated with LGSI, but the association is mainly supported by a strong independent correlation between waist circumference and high hs.CRP levels. In the absence of this specific MS component, it seems that the contribution of MS to LGSI would be modest at best.