The present study aimed to examine the pre- and post-treatment effect of Nigella sativa water extract and crude oil against hepatotoxicity - induced by carbon tetrachloride in rats. The Nigella sativa extract or crude oil was screened for estimating their total phenolic contents and free radical scavenging activity. They have a high antioxidant activity due to phenolic compounds. Protective role of the Nigella sativa water extract and crude oil against carbon tetrachloride -induced alternation in blood biochemical and liver was evaluated. The examined extracts were administered 28 days before and 28 days after concomitantly with carbon tetrachloride for water extract and crude oil. Blood samples were determination of serum aminotransferases activity (ALT and AST), total protein (TP) albumin (Alb), urea, creatinine, and the activities of antioxidants such as glutathione-S-transferease (GST), superoxide dismutase (SOD),catalase (CAT) and malonialdehyde (MDA) content. The results detected that the  intraperitoneal injection of carbon tetrachloride motivate the increase in ALT and AST activity also urea, creatinine and liver MDA, meanwhile a high decrease in the levels of total protein, albumin and liver GST, SOD, CAT were obtained. The results revealed that Nigella sativa water extract or crude oil had a protective effect against the carbon tetrachloride -induced.