The pathogenesis of excess cardiovascular risk in type 1 diabetes is unclear. LDL cholesterol is only weakly predictive, and its concentration is often normal in type 1 diabetes. We therefore examined whether markers of LDL oxidation such as antibodies to oxidized LDL (Ab-OxLDL) and LDL-containing immune complexes, rather than LDL concentration, were predictive of coronary artery disease (CAD) in type 1 diabetes. This nested case-control study from an epidemiologic cohort study included 49 incident cases of myocardial infarction (MI), angina, or CAD death and 49 age-, sex-, and duration-matched control subjects. Ab-OxLDL was measured by enzyme immunoassay and the apolipoprotein B (ApoB) content of immune complexes (ApoB-IC) precipitated by polyethylene glycol by immunoelectrophoresis in baseline stored samples. Ab-OxLDL was inversely, and ApoB-IC directly, related to subsequent CAD. In multivariate analyses, Ab-OxLDL remained a significant independent predictor along with previously recognized predictors, hypertension and Beck depression score. In conclusion, oxidation of LDL and the immune response it elicits may play a role in predicting the development of CAD in type 1 diabetes and explain at least some of the enhanced CAD risk in type I diabetes.