Abstract: The goal of this study is to evaluate the utility of acoustic radiation force impulse (ARFI) elastography for determining the severity grade of rat liver steatosis. Steatosis is induced in the rat livers by gavage feeding of a high fat emulsion. Liver mechanics are measured ex vivo using shear wave velocity (SWV) induced by acoustic radiation force. The results show that there is a significant difference between the normal group (2.25±0.52) m/s and steatosis group (2.83±0.37) m/s (P < 0.05). However, there are no significant differences in SWV measurements between the steatosis grades. SWV values do not correlate with the early grade of inflammation. In conclusion, ARFI elastography is a promising method for differentiating normal rat liver from the rat liver with steatosis, but it cannot reliably predict the grade of steatosis in rat livers. The early grade of inflammation activity does not significantly affect the SWV meas-urements.