The antioxidants activities are decreased in the serum of women with preeclampsia. This study was aimed to determine the serum level and antioxidant activity of ceruloplasmin in preeclamptic women with gestational age over than 28 weeks. In a cross-sectional and descriptive-analytic study performed on 60 patients with preeclampsia (30 with mild and 30 with severe preeclampsia) and 30 women with normal pregnancy (control) in Tabriz al-Zahra Hospital, serum level and antioxidant activity of ceruloplasmin was evaluated. The mean gestational age was 32.94+/-2.79 week in mild preeclampsia group, 32.17+/-3.00 week in severe preeclampsia group and 32.46+/-4.04 week in control group (p = 0.821). The mean serum level of ceruloplasmin was 0.62+/-0.16 g L-1 in mild preeclampsia group, 0.61+/-0.23 g L-1 in severe preeclampsia group and 0.47+/-0.16 g L-1 in control group. The serum ceruloplasmin in control group was significantly lower (p = 0.006). The mean antioxidant activity of ceruloplasmin was 562.54+/-139.79 in mild preeclampsia group, 556.21+/-190.94 in severe preeclampsia group and 427.62+/-162.14 in control group. The antioxidant activity was measured as production of mg dL-1 of a colored product. The antioxidant activity of ceruloplasmin in control group patients was significantly lower (p = 0.002). Significant linear positive correlation was found between serum level of ceruloplasmin and antioxidant activity of ceruloplasmin (p<0.001 and r = 0.910). Serum level of ceruloplasmin is significantly lower in normal pregnancy than mild and severe preeclampsia. Antioxidant activity of ceruloplasmin is significantly lower in normal pregnancy than mild and severe preeclampsia.