Bicuspid aortic valves (BAVs) represent a wide morphologic and functional spectrum. In coarctation of the aorta, BAVs are common, but the proportion of BAV subtypes and their relation to aortic dimensions and development of late valve dysfunction are unknown. Sixty-two cardiovascular magnetic resonance investigations of patients with coarctation of the aorta were reviewed with respect to aortic valve morphology, aortic valve function, and aortic dimensions. BAVs were identified in 45 patients (72.6%), of which 13 (20.9%) were type-0 (two commissures), 28 (45.1%) type-1 (three commissures but fusion of one commissure with a raphe) and 4 (6.5%) valves were bicuspid but not possible to classify further. Patients with BAVs type-0 had larger dimensions in their sinus of Valsalva (35.5 ± 6.8 vs. 29.7 ± 2.7 mm, p = 0.002), ascending aorta (33.1 ± 6.2 vs. 26.0 ± 4.3 mm, p = 0.005) and sino-tubular junction (29.3 ± 7.4 vs. 24.2 ± 3.5 mm, p = 0.040) compared with tricuspid aortic valves (TAVs). Moderate and severe aortic valve disease was more common in BAV type-0 compared with BAV type-1 (p = 0.030) and TAV (p = 0.016). In a multivariate linear regression model BAV type-0 (p = 0.005), BAV type-1 (p = 0.011), age (p < 0.001), patient height (p = 0.009), and aortic valve disease (p = 0.035) were independently associated with increased diameter of the ascending aorta (R (2) of the model 0.54, p < 0.001). BAV type-0 is relatively common in coarctation of the aorta. Both BAV type-0 and type-1 are associated with increased diameter of the ascending aorta but this association is stronger for BAV type-0. Development of aortic valve disease is more common in BAV type-0 than in BAV type-1. Discrimination between BAV subtypes may potentially provide clinical and prognostic information in patients with coarctation of the aorta.