The present study examined von Willebrand factor (vWF) levels and ADAMTS13 activity in pregnant and severe preeclamptic women in order to shed light on the prothrombotic state in severe preeclampsia. Thirty healthy women of childbearing age, 22 second trimester pregnant women, 30 third trimester pregnant women and 10 severe preeclamptic patients were recruited in this study. ADAMTS13 activity was determined by the FRETS-vWF73 assay and vWF antigen (vWF: Ag) levels by an enzyme-linked immunosorbent assay. The results showed that there were statistically significant differences in plasma vWF antigen levels between the severe preeclamptic and third trimester pregnant women, between third and second trimester pregnant women (P < 0.05). The third trimester pregnant women had significantly lower plasma ADAMTS13 activity than second trimester pregnant women (P < 0.05). Nevertheless, no significant differences in plasma ADAMTS13 activity were found between severe preeclamptic patients and the third trimester pregnant women (P > 0.05). In conclusion, plasma ADAMTS13 activity is normal in severe preeclampsia despite the increased vWF: Ag levels. Prothrombotic state is involved in the pathogenesis of severe preeclampsia, as a result of endothelial injury.