The ethanolic extract of Hypnea muciformis (red algae) was tested for hepatoprotective activity against experimentally induced liver damage by Carbon tetrachloride (CCl4) in male albino rats. The levels of serum enzymatic and biochemical parameters such as serum glutamate oxaloacetate transaminase (SGOT), Serum glutamate pyruvate transaminase (SGPT), alkaline phosphatase (ALP), lactate dehydrogenase, 5' nucleotidase, bilirubin, creatinine, urea, triglycerides, lipid peroxides and albumin were determined. The CCI4 induced lesions in the liver significant increased the levels of serum marker enzymes SGPT and SGOT, bilirubin, creatinine and decreased urea. The oral treatment with ethanolic extract of H. muciformis exhibited significant hepatoprotective activity by reducing the CCL4 caused changes in the biochemical parameters such as total protein, total bilirubin, total cholesterol, triglycerides, and urea. These parameters were restored towards the normal levels as shown by the enzymatic tests. In addition, H. muciformis significantly decreased the liver weight of CCl4 intoxicated rats. Apparently the H. muciformis extract interfered with the free radical formation, which resulted in hepatoprotective activity. Acute toxicity studies revealed that the LD50 value was more than 3 g/kg body weight. These results clearly indicated that this seaweed contained some active principles in its ethanolic extract which acted as an antidote against the hepatotoxicity induced by CCl4.