BACKGROUND Although isolated left ventricular noncompaction (ILVNC) has been described almost two decades ago, our knowledge about its diagnosis, presentation, echocardiographic features and clinical outcome is sparse. We aimed to assess the echocardiographic and clinical characteristics of ILVNC in a group of patients referred to our center. METHODS Patients who were referred to a tertiary referral center, affiliated with Mashhad University of Medical Sciences, with primary diagnosis of dilated cardiomyopathy underwent comprehensive echocardiographic evaluation. The diagnosis of ILVNC was made based on the presence of two-structural layer in myocardium; ratio of noncompacted to compacted layers more than 2, and excessive trabeculation in the left ventricle. RESULTS Final diagnoses of ILVNC were made in 42 patients. Mean age of patients was 32.9 ± 15.6 years (ranging from 9 to 70 years). Females comprised a higher proportion of patients (61.9%) and shortness of breath was the most reported symptom among patients (47.6%). Non-compacted layers were detected in inferior and lateral segments of apex in 97.6% of patients. A total of 26 (61.9%) patients had left ventricle (LV) dysfunction (defined as ejection fraction less than 50%). The only factor that showed significant association with LV dysfunction was the number of affected segments with noncompaction (P = 0.008). Reduced ejection fraction was not associated with either age or sex (P = 0.437 and P = 0.206, respectively). CONCLUSIONS Based on the result of the current study, it can be suggested that apex of the heart is the most common site of noncompaction and increasing numbers of affected segments might be associated with LV dysfunction.