Obesity is a global problem and in aspects of lethal ethanol intoxications virtually unexplored. The cause of death in ethanol intoxication is generally considered to be suppression of the respiratory function. Previous research indicates that respiratory function is more vulnerable in obese subjects than in those of normal weight. We hypothesized that lethal blood alcohol concentration (BAC) is lower in obese subjects compared to those of normal weight. We used the Swedish medicolegal autopsy register and identified all medicolegal autopsy cases in Sweden during the period from 1999 to 2013 (N=79,060), and identified 1545 cases with ethanol intoxication identified as the primary cause of death. We studied the association between body mass index and lethal BAC using logistic regression models that we adjusted using several potential confounders such as age, sex, drugs, and extent of decomposition. We observed an association between obesity and lower lethal BACs. The estimated adjusted odds ratio of the association between obesity and a lethal BAC >3‰, using subjects of normal weight as reference, was 0.54, 95% confidence interval: 0.39-0.74. The result indicates that in obese subjects the lethal BAC is lower than in those of normal weight.