Evidence regarding the use of dual antiplatelet therapy and oral anticoagulation (i.e., triple therapy) in acute coronary syndromes (ACS) is limited. We evaluated the characteristics associated with the choice of triple therapy in ACS. Using the Get With The Guidelines (GWTG) Coronary Artery Disease national registry, we studied patients with ACS at 361 sites in the United States from 2004 to 2007. Both univariate analysis and multivariate logistic regression analysis were used to assess the factors associated using triple therapy on discharge. The Generalized Estimating Equation method was used to account for within-hospital clustering in modeling. A total of 86,304 patients presented with ACS during the study period. At discharge, 3,933 patients (4.6%) were prescribed triple therapy, 60,716 patients (70.4%) received dual antiplatelet therapy, 2,348 patients (2.7%) received single antiplatelet therapy plus oral anticoagulation, 19,065 patients (22.1%) received antiplatelet monotherapy, and 242 patients (0.3%) received oral anticoagulation alone. Patients with a history of atrial fibrillation (odds ratio 7.01, 95% confidence interval 6.06 to 8.12; p <0.001), documented new-onset atrial fibrillation (odds ratio 3.76, 95% confidence interval 2.87 to 4.93; p <0.001), or history of atrial flutter (odds ratio 3.38, 95% confidence interval 2.15 to 5.32; p <0.001) were more frequently discharged with triple therapy. In conclusion, for patients with ACS, atrial fibrillation and atrial flutter were most strongly associated with the use of triple therapy; however, this therapy was used less often than dual or single antiplatelet therapy.