BACKGROUND AND OBJECTIVE: To ascertain whether interdental cleaning behaviours of Australian adults were associated with lower levels of plaque, gingivitis and periodontal disease. MATERIAL AND METHODS: Data were obtained from the National Survey of Adult Oral Health 2004-06. Outcome variables were three indicators of oral hygiene outcomes (the presence or not of dental plaque, dental calculus and gingivitis) and two of periodontal disease (the presence or not of at least one tooth with a periodontal pocket or clinical attachment loss of ≥ 4 mm). The independent variable was classified into the following three groups: regularly clean interproximally 'at least daily' (daily+); 'less than daily' (< daily); and 'do not regularly clean interproximally' (reference group). Poisson regression with robust variance estimation was used to calculate prevalence ratios (PRs) and 95% confidence intervals (95% CIs) relative to the reference group, adjusted for covariates. RESULTS: Regular self interdental cleaning was associated with less dental plaque (< daily, PR = 0.89, 95% CI = 0.84, 0.95; and daily+, PR = 0.89, 95% CI = 0.82, 0.96), less dental calculus (< daily, PR = 0.88, 95% CI = 0.80, 0.97; and daily+, PR = 0.79, 95% CI = 0.70, 0.89) and lower levels of moderate/severe gingivitis (daily+, PR = 0.85, 95% CI = 0.77, 0.94). Periodontal pocketing was less likely for the < daily group (PR = 0.61, 95% CI = 0.46, 0.82), but was not associated with daily+ cleaning (PR = 0.99, 95% CI = 0.663, 1.49). There was not a significant association between interdental cleaning and clinical attachment loss (< daily, PR = 0.90, 95% CI = 0.77, 1.05; and daily+, PR = 1.17, 95% CI = 0.95, 1.44). CONCLUSION: Regular interdental cleaning was associated with better oral hygiene outcomes, such as dental plaque and gingivitis, although there was no significant association between regular interdental cleaning and clinical attachment loss.