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The presence of periodontal pathogens is associated with an increased prevalence of rheumatoid arthritis (RA). The systemic antibody response to epitopes of these bacteria is often used asa proxy to study correlations between bacteria and RA. The primary aim of the present study is toexamine the correlation between the presence of Aggregatibacter actinomycetemcomitans (Aa) in theoral cavity and serum antibodies against the leukotoxin (LtxA) produced by this bacterium. Thesalivary presence of Aa was analyzed with quantitative PCR and serum LtxA ab in a cell culturebased neutralization assay. The analyses were performed on samples from a well-characterized RAcohort (n = 189) and a reference population of blood donors (n = 101). Salivary Aa was present in15% of the RA patients and 6% of the blood donors. LtxA ab were detected in 19% of RA-sera andin 16% of sera from blood donors. The correlation between salivary Aa and serum LtxA ab wassurprisingly low (rho = 0.55 [95% CI: 0.40, 0.68]). The presence of salivary Aa showed no significantassociation with any of the RA-associated parameters documented in the cohort. A limitation of thepresent study is the relatively low number of individuals with detectable concentrations of Aa insaliva. Moreover, in the comparison of detectable Aa prevalence between RA patients and blooddonors, we assumed that the two groups were equivalent in other Aa prognostic factors. These limitations must be taken into consideration when the result from the study is interpreted. We concludethat a systemic immune response to Aa LtxA does not fully reflect the prevalence of Aa in saliva. Inaddition, the association between RA-associated parameters and the presence of Aa was negligiblein the present RA cohort.