BMI has been inversely associated with risk of completed suicide in several cohort studies, but putative mechanisms for this association and its generalizability throughout the United States are uncertain. We ascertained recent population-based, state-level data on rates of obesity, completed suicide (by method), firearm ownership, smoking, major depression, income, education, white race, and nonmetropolitan residence, compiled from federal agencies and surveys, and determined the adjusted population-weighted correlations of statewide obesity rates with measures of completed and attempted suicide. Statewide prevalence of obesity was strongly inversely correlated with age adjusted suicide rate (multivariable-adjusted r=-0.66; P<0.001). The correlation was somewhat stronger for rates of nonfirearm-related (r=-0.75; P<0.001) than firearm-related suicides (r=-0.53; P<0.001), and was of similar magnitude as the positive correlations of firearm prevalence with suicide rate (r=0.75; P<0.001) or of obesity with prevalence of diabetes (r=0.41; P=0.006). In analyses of fatal and nonfatal suicidal acts, obesity rates were inversely correlated with rates of suicidal acts using firearms (r=-0.53; P=0.02) and suffocation (r=-0.76; P<0.001) but not other methods. Obesity rates were also inversely correlated with the case-fatality ratios of acts using poisoning (r=-0.51; P=0.01). Thus, statewide rates of obesity are strongly inversely correlated with rates of completed suicide in multivariable analyses, a finding that appears to relate to fewer attempts by suffocation and a lower case-fatality ratio for poisonings, although the mechanism for the inverse correlation with firearm-related suicides requires further elucidation.