Lycopene is the important pigment responsible for the characteristic red color of tomato, it has attracted attention due to its biological and physicochemical properties, especially related to its effects as a natural antioxidant. The objective of this study was to investigate the antioxidant effect of the lycopenes obtained from the extract of tomato on the peroxidation of hepatic microsomes membranes. Rat liver microsomes where incubated with different concentrations of extract (2, 4, 6, 8 μg) in an in vitro non-enzymatic ascorbic acid-Fe+2 system in order to determine the oxidative effect on membranes and to quantify peroxidation level in standardized conditions. Peroxidation was quantified in a liquid scintillation counter Packard 1900 TR by chemiluminescence in cpm (counts per minute). Microsomal membranes without extract were used as controls. Analyzing the effect of lycopene (tomato extract), was observed that the total cpm/mg protein originated from light emission: chemiluminescence, was statistically lower in samples obtained from lycopene group than in the control group (without lycopene), the antioxidant effect found was not dependent concentration.