Cardiac magnetic resonance (CMR) is useful for the diagnosis of left ventricular noncompaction (LVNC). However, there are limited data regarding its prognostic value. The goal of this study was to evaluate the prognostic relevance of CMR findings in patients with LVNC. A total of 113 patients with an echocardiographic diagnosis of LVNC underwent CMR at 5 referral centers. CMR diagnostic criterion of LVNC (noncompacted/compacted ratio >2.3 in end-diastole) was confirmed in all patients. We performed left ventricular (LV) and right ventricular quantitative analysis and late gadolinium enhancement (LGE) assessments and analyzed the following LVNC diagnostic criteria: left ventricular noncompacted myocardial mass (LV-ncMM) >20% and >25%, total LV-ncMM index >15 g/m(2), noncompacted/compacted ratio ≥3:1 ≥1 of segments 1 to 3 and 7 to 16 or ≥2:1 in at least 1 of segments 4 to 6 of the American Heart Association model. Outcome was a composite of thromboembolic events, heart failure hospitalizations, ventricular arrhythmias, and cardiac death. At a mean follow-up of 48 ± 24 months, cardiac events (CEs) occurred in 36 patients (16 heart failure hospitalizations, 10 ventricular arrhythmias, 5 cardiac deaths, and 5 thromboembolic events). LV dilation, impaired LV ejection fraction, and LV-ncMM >20% was significantly more frequent in patients with CEs. LV fibrosis was detected by using LGE in 11 cases. CMR predictors of CEs were LV dilation and LGE. LGE was associated with improved prediction of CEs, compared with clinical data and CMR functional parameters in all 3 models. No CEs occurred in patients without dilated cardiomyopathy and/or LGE. In patients with LVNC evaluated by using CMR, the degree of LV trabeculation seems to have no prognostic impact over and above LV dilation, LV systolic dysfunction, and presence of LGE.