Preeclampsia is a pregnancy specific disorder and is thought to be associated with generalized endothelial dysfunction. P-selectin, an adhesion molecule, mediates the interaction of monocytes, platelets, and endothelial cells. Increased P-selectin levels and altered lipid and lipoprotein metabolism were reported in preeclampsia and during pregnancy. In order to investigate the relationship between serum P-selectin and lipoprotein(a), and other lipid parameters, 28 preeclampsia [13 severe (group I) and 15 mild preeclampsia (group II), 15 healthy pregnant (group III) and 20 non-pregnant (group IV)] women were investigated. Serum P-selectin, lipoprotein(a), total cholesterol, triglyceride, and high density lipoprotein cholesterol were measured and low-density lipoprotein cholesterol was derived. Serum P-selectin concentrations were consistently and significantly higher in the severe preeclampsia group than in the mild preeclampsia, healthy pregnancy, and non-pregnant control groups (P<0.0001, for all). The mild preeclampsia group also had increased serum P-selectin concentrations compared with the healthy pregnancy group and non-pregnant controls (P<0.05 and P<0.0001, respectively). Serum P-selectin and lipoprotein(a) levels revealed a significant and linear increase with the severity of preeclampsia. There were also significant (in groups I and II) and borderline (in groups III and IV) correlations between P-selectin and total cholesterol. The present study suggests that P-selectin may be an additional risk marker for preeclampsia, and may be useful in distinguishing women with mild and severe preeclampsia and normal pregnancy.