Objective: left ventricular noncompaction is a congenital malformation characterized by a myocardium organized into two layers, one compacted and one noncompacted. We aimed to quantify myocardial function, perfusion, and delayed enhancement using MRI in patients with left-ventricular noncompaction and to compare these results with those of normal patients. Material and methods: we included 12 patients with a myocardial noncompaction / compaction ratio > 2.3 at end-diastole in at least one segment apart from the apex and 12 healthy subjects matched for age and sex. We calculated the end-diastolic and end-systolic volumes, stroke volume, ejection fraction, cardiac output, myocardial volume and mass, end-diastolic thickness, and left-ventricular wall thickening and motion. From the delayed enhancement images, we obtained the volume and percentage of hyperenhanced myocardium. Student's t test was used to compare groups. Results: we observed a statistically signifi cant increase in end-diastolic and end-systolic volumes in patients with left-ventricular noncompaction, as well as decreased ejection fraction, wall motion, and relative maximum upslope in segments 4, 9, and 10. No signifi cant differences were found in delayed hyperenhancement. Conclusion: MRI quantification revealed decreased systolic cardiac function and decreased perfusion (lower relative maximum upslope) in the lower segments in patients with noncompaction. (C) 2008 SERAM. Published by Elsevier Espana, S.L. All rights reserved.