The ancient medicinal plant Silybum marianum has been used to cure various diseases for centuries. 
Silymarin is the main bioactive ingredient found in these plant seeds. Thus, the purpose of this study was 
to evaluate the ability of silymarin and nano silymarin to alleviate oxidative stress and ameliorate 
damaged histoarchitecture of the liver in Ehrlich ascites carcinoma-bearing mice. HPLC analysis of nano 
silymarin flavonoid compounds in milk thistle seed extract was performed. A total of 60 Swiss albino 
female mice were randomly separated into four equal groups. The first group was assigned as the normal 
control. An intraperitoneal injection of 2.5 x 10 6 EAC cells was administered to each of the three 
remaining groups. As the EAC positive control group, the second group didn't receive additional 
treatment. Mice in the third and fourth groups ingested orally Silymarine and nano silymarine at a dose of 
100 mg/kg b.w. daily for 6 weeks. Markers of oxidative stress and tumors, as well as enzymatic and non- 
enzymatic antioxidants, were assessed in each experimental group. Furthermore, a liver histopathological 
examination was performed. The findings showed that mice with induced EAC had damaged liver 
histoarchitecture, low levels of enzymatic and non-enzymatic antioxidants, and high levels of tumor and 
oxidative stress markers. Administration of silymarine and nano silymarine to EAC-bearing mice reduced 
oxidative stress and improved the histoarchitecture of the damaged liver.