Abstract Background: Cystic fibrosis may lead to left ventricular dysfunction. This dysfunction can be documented by methods such as tissue doppler echocardiographic imaging and two-dimensional speckle tracking echocardiography in early stage. Patients and Methods: A total of 34 patients diagnosed with cystic fibrosis (mean age and SD 9.9±4.9 years) and 37 healthy control subjects with a comparable gender and age distribution (mean age 9.8±4.3) were studied. The results for the two groups were compared along with the results of published reports. Result: Control group had higher diastolic and systolic dimentions compared to the patient group in M-mode measurements of left ventricle by conventional echocardiography (p <0.05). There was no significant relationship between the groups in terms of the dimensions of systolic and diastolic measurements of interventricular septum and posterior wall of left ventricle, and ejection fraction. Pulmonary artery systolic pressure was significantly higher in the patient group (p<0.001). Myocardial performance indices of left ventricle free wall and interventricular septum were increased in the patient group compared to the control group (p<0.05). ). As measured by speckle tracking echocardiography, 7 segments in left ventricular myocardial longitudinal strain and 3 segments in left ventricular myocardial circumferential strain showed significant reductions in patients with cystic fibrosis compared to controls (p <0.05). Conclusions: Tissue doppler echocardiographic imaging and speckle tracking echocardiography may help identifying subclinical left ventricular dysfunction in cystic fibrosis patients with unremarkable conventional echocardiography. Its may be considered for the routine follow-up of cystic fibrosis patients.