Objectives: The exact pathogenesis of neural tube defects (NTDs) is poorly understood. We aimed at evaluating maternal anti-oxidant capacity (ceruloplasmin level, myeloperoxidase and catalase activity) in pregnancies complicated by NTDs. Material and methods: Fifty-four mothers with NTD-affected pregnancies and 61 healthy mothers, matched for gestational age, were recruited. Maternal venous blood samples were obtained after detailed fetal ultrasound examination to measure myeloperoxidase, catalase activity and ceruloplasmin levels. The clinical characteristics of all participants were collected. Results: Maternal blood catalase activity was significantly lower in the study group (117.1 +/- 64.8 kU/L) as compared to controls (152.2 +/- 110.6 kU/L) (p = 0.044). Maternal blood ceruloplasmin levels were also significantly lower in the study group (180.5 +/- 37.7 U/L) as compared to controls (197.9 +/- 35.9 U/L) (p = 0.012). Myeloperoxidase activity was similar in both groups (112.6 +/- 22.2 U/L vs. 113.6 +/- 38.1 U/L) (p = 0.869). Conclusions: In the present study, maternal blood ceruloplasmin level and catalase activity were found to be lower in NTD-affected pregnancies as compared to healthy controls. Thus, it seems safe to conclude that impaired antioxidant capacity may play a role in the development of NTDs during pregnancy, in addition to the genetic, environmental and metabolic factors.