Periodontitis is known to be a risk factor for abdominal aortic aneurysm (AAA). However, the influence of periodontitis on AAA in Japanese patients has not yet been elucidated. The aim of this clinical investigation was to assess the relationship between periodontal bacterial burden in AAA patients.We studied 12 AAA patients and 24 age- and sex-matched non-AAA cardiovascular patients. We examined periodontitis and the presence of the periodontal pathogens Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, and Prevotella intermedia in oral samples using polymerase chain reaction assays.We found that the AAA patients had deeper pocket depth compared to the non-AAA patients (3.53 ± 0.38 mm versus 2.67 ± 0.17 mm, P < 0.05). However, the populations of periodontal bacteria were comparable between the two groups. Periodontitis may have a greater effect on aneurysm progression compared to other cardiovascular diseases.