BACKGROUND : Obesity is associated with many cardiovascular risk factors. This study aimed to evaluate the independent association between obesity and pulmonary embolism. METHODS : We used the International Classification of Diseases, Ninth Revision, Codes for obesity and pulmonary embolism from the Nationwide Inpatient Sample database. We randomly selected the 1992 and 2002 databases, which are 10 years apart, as the two independent population samples. We performed uni- and multivariate analyses to evaluate any association between obesity and pulmonary embolism. RESULTS : The 1992 database consisted of a total of 6,195,744 patients. Obesity was present in 93,568 patients. Pulmonary embolism occurred in 0.7% of obese patients vs. 0.3% of the control population (odds ratio [OR], 2.32; 95% confidence interval [CI] 2.2-2.4; p<0.0001). The 2002 database consisted of a total of 299,010 obese patients. Pulmonary embolism occurred in 0.9% of obese patients vs. 0.4% of the control population (OR, 2.36; 95% CI, 2.19-2.41; p<0.0001). After adjusting for age and many risk factors, obesity remained strongly associated with pulmonary embolism (for 1992, OR, 2.1; 95% CI, 2.0-2.3; p<0.0001 and for 2002, OR, 2.2; 95% CI, 2.1-2.3; p<0.0001). CONCLUSIONS : Obesity has been consistently associated with pulmonary embolism over the years studied using a large inpatient database. This association has been persistent over a period of 10 years and is consistent with the negative effects of obesity on the cardiopulmonary system.