Objective: To investigate the expression of catechol-O- methyltransferase (COMT) in placentas from term preeclampsia patients in a Chinese cohort and to analyze the relationships between COMT and mean artery pressure (MAP), serum uric acid and 24-hour urine protein. Methods: 15 term pregnant patients with preeclampsia and 15 normal pregnant women were enrolled. Clinical characteristics and placental tissue were collected. Placental COMT expression was determined by quantitative real-time PCR technique and immunohistochemistry. Results: The level of COMT mRNA in placentas from the preeclampsia group was significantly decreased than that in the normal pregnant women (0.00179 ± 0.00051 vs. 0.00289 ± 0.00066, t = 5.145, P < 0.001). Adjusted by age and body mass index (BMI), the COMT expression was negatively correlated with serum uric acid (r = ?0.660, P < 0.001), 24-hour urine protein (r = ?0.717, P < 0.001) and MAP (r = ?0.619, P < 0.001). Conclusion: The decreased expression of COMT in placentas from term preeclamptic patients and the significant relation between COMT and severity index of preeclampsia suggest that COMT may play a role in the pathogenesis of term preeclampsia.