The hydroalcoholic extract of the leaves of Rosmarinus officinalis (HE), a species of medicinal value, and its constituent rosmarinic acid (RA) were evaluated for hepatoprotective in the acetaminophen-induced liver damage model. Groups of Wistar albino rats (n=6) were pre-administered with HE (100, 250 and 500 mg/kg, p.o.) and RA (10, 25 and 50 mg/kg, p.o.) prior to a single dose of acetaminophen (APAP, 600 mg/kg body weight; p.o). The hepatoprotective activity of HE extract was observed through histopathological analysis and reduction of the level of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP). These observations were comparable to the normal group prior to APAP administration. Group that was treated with APAP alone exhibited high levels of transaminases and ALP. The obtained results from the present study suggested that HE may prevent APAP-induced hepatic injuries. RA did not displayed significant hepatoprotective activity against APAP-induced liver damage.