OBJECTIVES:Obesity and periodontitis are public health issues in Australia. This study aimed to determine the association between overweight/obesity and periodontitis in Australian adults. MATERIALS AND METHODS:The cross-sectional National Survey of Adult Oral Health 2004-2006 data were analysed. Body mass index was calculated, and a self-reported questionnaire was used to measure the estimated daily intake of added sugar. The mean number of sites with probing depth (PD) ≥ 4 mm and clinical attachment loss (CAL) ≥ 4 mm and presence of periodontitis were used as outcome measures. CDC/AAP periodontitis case definition was adopted. Bivariate analyses and multiple variable regression models were constructed. RESULTS:The study sample was 4,170 participants. The proportion of people that were overweight/obese was 51.9% [95% confidence interval (CI): 48.1%, 54.1%]. Overall 21.3% (95% CI: 19.3%, 23.5%) people experienced periodontitis. The mean number of sites with PD ≥ 4 mm and CAL ≥ 4 mm were recorded as 0.7 (95% CI: 0.5, 0.9) and 2.4 (95% CI: 2.1, 2.6), respectively. Multiple variable analysis suggested that periodontal parameters [sites with PD ≥ 4 mm (0.13, 95% CI: -0.86, 0.35) and sites with CAL ≥ 4 mm (0.11, 95% CI: -0.58, 0.35) and presence of periodontitis (1.23, 95% CI: 0.96, 1.57)] were not associated with overweight/obesity when controlled for putative confounders. CONCLUSION:A positive association was found between overweight/obesity and periodontitis (PD and CAL). However, the statistical significance disappeared in the multiple variable regression analysis, where age, sex, smoking and dental visiting behaviour were found to be key determinants of periodontitis.