Objective:Although immunity to malaria is reduced in pregnancy,the matal immune system still continues to respond to malaria infection by the production of antibodies.IgG has been reported to play significant role in immune response against P.falciparum.Anti-MSP-1 1 9 antibody and reactive oxygen species have been shown to be protective against malaria infection in children.This work assessed the response of anti-MSP-1 1 9 antibody (a promising blood stage vaccine candidate antigen)and oxidative stress in 250 pregnant women.Methods:Blood samples were collected in dry and wet seasons.Plasmodium falciparum infection was determined by mi-croscopy,anti-MSP-1 1 9 IgG level was investigated using ELISA.Malondiadelhyde (MDA)and reduced gluta-thione (GSH)were used as indicators of oxidative stress and they were quantified spectrophotometrically.Re-sults:Parasitaemia was significantly higher (P <0.05)in wet than dry season and its level decreased with gravidity.There was a significant increase (P <0.05)in anti-MSP-1 1 9 IgG and MDA levels in the dry than wet season.Anti-MSP-1 1 9 IgG and MDA levels were significantly higher in P.falciparum positive primigravidae than P.falciparum negative primigravidae in both wet and dry seasons.In wet season anti-MSP-1 1 9 IgG level was significantly increased (P <0.05)in P.falciparum positive multigravidae than P.falciparum negative. The anti-MSP-1 1 9 IgG and MDA were significant higher in P.falciparum positive multigravidae than primigravi-dae.Reduced glutathione (GSH)level was significantly reduced (P <0.05)among malaria positive than ma-laria negative patients in both seasons.Conclusion:This study suggests that IgG and MDA response were pos-itively associated with the presence of malaria infection.