Based on an elevated D-dimer, vast numbers of patients who have no risk factors are routinely worked up for PE with a battery of tests, including computed tomographic angiography (CTA) of the chest which exposes patients to significant radiation. We are not certain whether this elaborate workup is warranted in this subset of population with no risk factors. To address this concern, it was felt that knowing positive predictive value (PPV) of D-dimer in predicting PE in patients with no risk factors would be helpful. However, to our knowledge, no studies were documented in the literature assessing PPV in those with no risk factors for PE. Hence this study was designed.