The usage of doxorubicin (DOX) as an anticancer drug in cancer patient may cause several side effects. One of that is cardiotoxicity by inducing the expression of nitric oxide synthase which may release nitric oxide (NO) resulting reactive oxygen species (ROS) in the cardiac. DOX needs to be combined with antioxidant since it could supressed ROS in the cardiac and reduce cardiomyopathy. Kelor (Moringa oleifera) is known as the source of antioxidant. This study aim to observe the treatment effects of ethanolic extract of kelor (EEK) on histopathology profile and concentration of NO in rats cardiac. The result from the hematoxylin-eosin staining showed that EEK improved the histopathology profile of rats’ cardiac. Compared with the DOX-only treatment, the structure of cardiac muscle cells treated by ethanolic extract of kelor is more well-arranged and the cells’ nucleus still visible. Concentration of NO was measured by cardiac puncture method. The result showed that the concentration of NO was decrease in line with increasing dose levels of EEK in combination with DOX. But at rats only given with EEK, the concentration of NO is quite high. In conclusion, EEK could be a cochemotherapy agent by reducing the cardiotoxicity effect of DOX.Keywords : doxorubicin, Moringa oleifera, nitric oxyde, histopathology