Preeclampsia is a multifactorial disease. Recent studies show that free radical induced endothelial injury may be a factor in pathogenesis of preeclampsia and that a biochemical imbalance occurs with an increase of oxidative stress, lipoperoxidation a nd deficient antioxidants. AIMS AND OBJECTIVESTo evaluate parameters of oxidative stress and antioxidant defense in preeclampsia and thereby find any aetiological correlation. MATERIALS AND METHODSStudy was carried on pregnant and non-pregnant women placed in four groups. This study was done to assess Malondialdehyde (MDA), as marker of oxidative stress and Total Antioxidant Capacity (TAC) measured by Ferric Reducing Ability of Plasma (FRAP) in normal pregnancy and preeclampsia and comparing with non-pregnant females. RESULTS Studyshows rise in MDA level highest in severe preeclampsia (192.8) followed by mild preeclampsia (151.8) than in normal pregnancy (105.9), and non-pregnant (95.8) showing significant increase in levels of MDA (p<0.0001) in preeclamptic patients. TAC measured by FRAP significantly highest in severe preeclampsia (1725.6) followed by mild preeclampsia (1507) than in normal pregnancy (1203.3) and although there was increase in TAC in normal pregnant compared to non-pregnant (1173.7), increase was statistically insignificant. CONCLUSIONPreeclampsia shows markedly increased oxidative stress as evidenced by significantly increased levels of malondialdehyde. There was strong correlation between total antioxidant capacity with severity of preeclampsia.