D-dimer is a product of cross linked fibrin degradation and is a measure of the amount of fibrin turnover. As such, D-dimer might be of utility in the prediction of both thrombotic and hemorrhagic events. Therefore, the aim of the present study was to evaluate whether elevated D-dimer levels on admission and at discharge could predict subsequent ischemic and hemorrhagic events in patients with acute myocardial infarction (AMI). D-dimer was measured on admission and at discharge in 461 out of a total of 3,602 patients in the HORIZONS-AMI trial, as part of the formal prespecified biomarker substudy. The predictive value for major adverse cardiovascular events (MACE) and non-CABG major bleeding after 3 year follow up was investigated by stratifying patients in groups of D-dimer level and comparing event rates using Kaplan-Meier and calculating hazard ratios using Cox proportional hazards models. D-dimer levels ≥ 0.71 μg/mL on admission were associated with an adjusted hazard ratio of 2.58 for MACE (p = 0.0014) and 4.61 for major bleeding (p = 0.0018). A discharge D-dimer level ≥ 1.26 μg/mL was associated with a higher risk for MACE by univariate analysis (HR 1.88, p = 0.037), but lost its significance after multivariate adjustment (HR 1.77, p = 0.070). High D-dimer levels on admission were associated with a higher risk of MACE and non-CABG major bleeding in STEMI patients undergoing pPCI.