Purpose : Production of oxygen free radical is believed to be a main mechanism of doxorubicin (DOX) induced cardiotoxidity. Carvedilol is non selective beta receptor blocker and is known to have antioxidant effects. We investigated the cardioprotective effect of carvedilol on doxorubicin treated rat hearts using 2-D echocardiography (ECHO) with 2-D speckle tracking and cardiac catheterization Methods and results: Thirty two male rats were divided into three groups. Group I (n=10); DOX only, Group II (n=11); Carvedilol (5mg/kg/day) + DOX, Group III (n=11); Carvedilol (10mg/kg/day) + DOX. DOX was intraperitoneally administered every other day (1.25mg/kg��16 times, a total of 20mg/kg) and carvedilol was orally administered by gastric gavage everyday by 4th week. Echocardiography (ECHO) was taken at baseline and at 8th week. dP/dt of left ventricle was obtained with cardiac catheterization at 8th week. Baseline ECHO parameters were not different between groups. At 8th week, LVEDV increased, LVEF and strain/strain rate worsened. In group II and III, the prophylactic carvedilol was not effective in preventing left ventricular functional deterioration by DOX (table). Neither of dP/dtmax nor dP/dtmin was different between groups. Longitudinal/circumferential strain rate were worse in group II and III than group I. Conclusions : Rat hearts treated with doxorubicin revealed dilatation and functional deterioration of the LV. At 8th week, there was no difference in LVEF or dP/dt between groups but 2-D speckle tracking ECHO showed worse strain rate in carvedilol pretreated groups. Carvedilol pretreatment had no advantage in prevention of doxorubicin induced cardiotoxicity by 8th week.