<p><b>STUDY OBJECTIVES: </b>To investigate the association between sleep disordered breathing (SDB) and severe chronic periodontitis.</p><p><b>DESIGN: </b>Cross-sectional data analysis from the Hispanic Community Health Study/Study of Latinos.</p><p><b>SETTING: </b>Community-based setting with probability sampling from four urban US communities.</p><p><b>PARTICIPANTS: </b>12,469 adults aged 18-74 y.</p><p><b>INTERVENTIONS: </b>None.</p><p><b>MEASUREMENTS AND RESULTS: </b>Severe chronic periodontitis was defined using the Centers for Disease Control and Prevention/American Academy of Periodontology case classification based on full-mouth periodontal assessments performed by calibrated dentists. SDB was evaluated in standardized home sleep tests, and defined as the number of apnea plus hypopnea events associated with ≥ 3% desaturation, per hour of estimated sleep. SDB was quantified using categories of the apnea-hypopnea index (AHI): 0.0 events (nonapneic); 0.1-4.9 (subclinical); 5.0-14.9 (mild); and ≥ 15 (moderate/severe). Covariates were demographic characteristics and established periodontitis risk factors. C-reactive protein was a potential explanatory variable. Using survey estimation, multivariable binary logistic regression estimated odds ratios (OR) and 95% confidence limits (CL). Following adjustment for confounding, the SDB and periodontitis relationship remained statistically significant, but was attenuated in strength and no longer dose-response. Compared with the nonapneic referent, adjusted odds of severe periodontitis were 40% higher with subclinical SDB (OR = 1.4, 95% CL: 1.0, 1.9), 60% higher with mild SDB (OR = 1.6, 95% CL: 1.1, 2.2) and 50% higher with moderate/severe SDB (OR = 1.5, 95% CL: 1.0, 2.3) demonstrating an independent association between SDB and severe periodontitis.</p><p><b>CONCLUSIONS: </b>This study identifies a novel association between mild sleep disordered breathing and periodontitis that was most pronounced in young adults.</p>