The free radical scavenger and antihepatotoxic activity from Rosmarinus tomentosus ethanolic extract and its fractions were studied, and also its membrane stabilizing activity in rat erythrocytes. Pretreatment with an ethanolic extract of R. tomentosus caused an important decrease in the CCl4-induced toxicity in rats liver, made evident by its effect on the levels of GPT and bilirubin in the serum and the malondialdehyde (MDA) concentration in the liver. These effects are similar to those produced by silymarin. The chloroformic fraction showed the greatest antihepatotoxic activity and the ethyl acetate fraction the greatest free radical scavenger activity.