It has been reported that mobile phones induce free radical formation. Epigallocatechin Gallate (EGCG) and N-Acetylcysteine (NAC) were recently found to be potent antioxidants. The present study was carried out to determine the protective effects of antioxidants namely EGCG and NAC against the mobile phone-induced oxidative stress. Three-month-old male Guinea pigs were randomized into 6 groups; sham group, not exposed to mobile phone, NAC group (300 mg kg(-1) ip, 7 days), 10 min mobile phone-exposed group with NAC, 10 min mobile phone-exposed group, EGCG group (25 mg kg(-1) ip, 7 days) and 10 min mobile phone-exposed group with EGCG. During the exposure external E fields were measured by NARDA EMR 300 and type 8.3 probe. Guinea pigs were exposed to RFR averaged as 11.2 +/- 0.5 V m(-1) for 10 min/day/7days. Malondialdehyde (MDA, an index of lipid peroxidation) were analysed as markers of oxidative stress. Plasma MDA levels increased in mobile phone exposed guinea pigs while EGCG causes a significant reduction of MDA levels, whereas NAC caused a significant increase in MDA levels. Also, MDA levels in mobile phone exposure group significantly increased with respect to sham exposure group. A number of studies have identified antioxidant species which show antioxidant effect in low-dose and pro-oxidant behaviour in high-dose. The increase of the lipid peroxidation at the treatment dose of NAC in guinea pigs may possibly be due to pro-oxidant behaviour. Besides, this study expressed that mobile phone exposure affect the level of lipid peroxidation of plasma.