Objective. To investigate the ability of two-dimensional longitudinal strain echocardiography (2DST), to detect the early doxorubicin cardiotoxicity. Patients and Methods. The study included 25 children with newly diagnosed acute lymphoblastic leukemia (ALL) aged 5-15 years and 30 healthy control children. They had echocardiographic examination with conventional 2-dimensional (2D), pulsed tissue Doppler (PTD), and 2DST echocardiography before and within 1 week after doxorubicin treatment. Results. There was no significant difference in left ventricle (LV) systolic and diastolic functions measured by conventional 2-D and PTD echocardiography between patients and controls. However, there was significant decrease in LV global and peak systolic strain detected by 2-DST echocardiography in study group than control. After doxorubicin treatment, there was no significant difference in LV systolic and diastolic functions measured by conventional 2-D and PTD echocardiography than before treatment except for prolonged IVCT and IVRT, but LV global and peak systolic strain was significantly lower after treatment. Conclusion. 2-D longitudinal strain echocardiography was more sensitive than conventional 2-D and PTD in detecting the early LV doxorubicin-induced cardiotoxicity in children with ALL.