An analytical cross-sectional study was conducted with 812 subjects aged 35-74 years in Prek Russey commune, Cambodia to detect some factors associated with severe periodontitis. Four calibrated examiners employed Community Periodontal Index (CPI) to ascertain periodontal pocket depth (PD) and loss of epithelial attachment (LA). A questionnaire was used to obtain tobacco and alcohol consumption habits. One hundred (12.3%) subjects had one or more sextants with > or =4 mm PD and > or =6 mm LA (severe periodontitis). Smoking, tobacco chewing and age were significantly associated with severe periodontitis in bivariate analysis while only age and quantified smoking remained significant in a logistic regression analysis. The impact of quantified smoking on severe periodontitis was almost negligible [OR: 1.0006 (95% CI: 1.0001, 1.001)] compared to that of age [OR ranged from 8.3 at 45-54 years to 22 at 65-74 years (95% CI: 3.1, 62.3)]. Nevertheless, both age and quantified smoking can be considered as factors associated with severe periodontitis in rural Cambodians.