Our objective was to determine if a brief didactic would improve Emergency Medicine (EM) resident performance at using a key evidence-based medicine (EBM) concept. We used a prospective, before and after, assessment of EM resident estimates of post-test pulmonary embolism (PE) probability for a defined pre-test probability, computed tomography (CT) and D-dimer results. The survey provided test sensitivity, and specificity for D-dimer and CT. Three months later, residents attended a brief didactic conference on how to use Fagan's Nomogram and likelihood ratios (LRs) to calculate post-test probability of disease. The accuracy of estimates of post-test PE probability was reassessed. The absolute percentage difference in resident estimates from the true post-test PE probabilities decreased from 14.5% (95% confidence interval [CI] 9.7%-19.9%) to 4.5% (95% CI 2.0-6.8%) after the educational intervention. This 10% effect size was statistically significant, p = 0.002. The study demonstrates the efficacy of the lecture method in teaching an EBM concept to EM residents.