To investigate the expressions of placental growth factor (PLGF) in placenta with hypertensive disorders of pregnancy (HDP), 45 women with HDP and 20 normally pregnant women were studied. Among 45 women with HDP, there were 23 cases of severe preeclampsia and one case of eclampsia. The location and level of PLGF proteins was determined by immunohistochemistry and Western blot. The expression of PLGF mRNA in placenta was assessed by reverse transcriptional-polymerase chain reaction (RT-PCR). The results showed that: (1) The distribution of PLGF in placenta with HDP was similar to normal one, which was mainly in the cytoplasm of villous syncytiotrophoblast and villous stroma; (2) The expression of PLGF protein was significantly decreased in placentas with mild and severe preeclampsia compared to the normal ones (0.3 +/- 0.4 vs 0.6 +/- 0.4, 0.2 +/- 0.5 vs 0.6 +/- 0.4, P < 0.01). There were no differences between the gestational hypertension placenta and normal one (0.5 +/- 0.6 vs 0.6 +/- 0.4, P > 0.05); (3) The transcription levels of the PLGF mRNA in placentas with preeclampsia were significantly lower than in normal groups (3.33 +/- 0.39 vs 4.87 +/- 0.60, 1.97 +/- 0.29 vs 4.87 +/- 0.60, P < 0.01), and no differences were found between the gestational hypertension placenta and normal groups. These findings suggest that the abnormal expression of PLGF in placentas is related to the pathogenesis of HDP.