Malaria in pregnancy constitutes a world-wide public health problem. With the objective of studying malaria in pregnancy, a cross-sectional, descriptive epidemiological study was carried out on 449 women, in mining areas of the San Isidro parish, municipality Sifontes, state of Bolívar, Venezuela, during 2005-2006. The Malaria incidence in pregnant women was 27.4%: 87% for Plasmodium vivax, 12.2% Plasmodium falciparum and 0.8% mixed infections. These infections appeared mainly during the second trimester (41.5%). Of the women studied, 71.5% presented symptoms and 26.2% had anemia. A higher proportion of abortions occurred among infected mothers with Plasmodium vivax (3/5); and there were 3.3% low-birth-weight neonates. A case of placental malaria (0.8%) for Plasmodium vivax was registered. An association was observed between mothers receiving chemoprophylaxis and the adequate weight of newborns (chi2 = 41 23gl. p < 0.0001), independently of the regularity of treatment. It is concluded that the routine administration of antimalarial quimioprophilaxis against P. vivax to pregnant women, could be justified in endemic areas. It is advisable to establish the routine diagnosis and opportune treatment during the prenatal practice in the transmission areas of malaria.