Left ventricular non-compaction (LVNC) is considered as a distinct form of cardiomyopathy with not well-understood background. We have decided to analyze markers differentiating patients with echocardiographic suspicion of LVNC in whom the diagnosis was confirmed or excluded by cardiac magnetic resonance (CMR). The CMR diagnosis of LVNC (NC/C ratio≥ 2.3) was confirmed in 15 of the 28 patients (54%). Patients with LVNC had lower right ventricular (RV) ejection fraction and more often RV trabeculation comprising the whole cavity at the level of RV apical segments. In the LVNC group there was significant correlation between LV and RV end-systolic volume and LV and RV ejection fraction and a trend towards correlation between LV and RV end-diastolic volume and mass. Our findings suggest that analysis of the RV may be used in differential diagnosis of LVNC and other diseases of the LV related to excessive trabeculation of this cavity.