Aims: To evaluate the role of metastin levels in the pathophysiology of pre-eclampsia and to determine whether there is a relationship between the severity of the disease and Doppler velocimetry measurements. Methods: This cross-sectional study included 89 pregnant women (50 healthy normotensive pregnant women, 15 patients with mild pre-eclampsia, and 24 patients with severe pre-eclampsia) at the third trimester of pregnancy. The maternal levels of plasma metastin were determined by enzyme-linked immunosorbent assay. The umbilical artery and uterine artery blood flow velocities were measured by transabdominal color and pulsed Doppler ultrasound. Results: Plasma metastin levels were lower in patients with pre-eclampsia than those in the normotensive pregnant women. Four patients with mild pre-eclampsia and seven patients with severe pre-eclampsia had abnormal Doppler velocimetry findings. Metastin levels of pre-eclamptic patients with abnormal Doppler velocimetry findings were significantly lower than those in patients with normal Doppler velocimetry findings. Plasma metastin levels negatively correlated with proteinuria in 24 hours and with mean arterial pressure in the cases of pre-eclampsia. Conclusions: The findings suggest that decreased maternal concentrations of plasma metastin may be involved in the pathogenesis of pre-eclampsia. Plasma metastin levels may be useful in the assessment of the severity of pre-eclampsia. However, further trials are needed to clarify the role of metastin in pre-eclampsia.