The antioxidative activity of pure compounds, foods and dietary supplements has been extensively studied in recent years. Activity assays are based on hydrogen ion transfer and electron transfer reactions which do not consider the bioavailability and metabolism issues. The mechanisms of action of antioxidants in biological system go beyond the antioxidant activity and scavenging free radicals. Animal models are expensive and not suitable for initial screening of antioxidative activity of plant extracts. Cell culture models are preferred in initial assessment of antioxidant bioactivity.The extract of Mentha piperita has been commonly used in the treatment of loss of appetite, common cold, bronchitis, sinusitis, fever,nausea, vomition and indigestion as an herbal agent. This piece of work will provide an insite into the antioxidative property of aqueous extract of Mentha piperita which is estimated by both electron transfer assays and cell culture models.