Objectives To test the hypothesis that lipocalin-type prostaglandin D synthase (L-PGDS), a marker of vascular epithelium disorders, may be a diagnostic for preeclampsia. Methods Plasma and urine were collected from 36 preeclamptic and 94 non-symptomatic patients throughout their pregnancies. L-PGDS concentrations were determined by sandwich ELISA assay. Receiver operating characteristic (ROC) curve validated the cut-off point of the assay. Results The plasma and urinary L-PGDS concentrations were significantly higher in the preeclamptic than the non-symptomatic patients. L-PGDS concentrations in the urine of normal pregnant women were higher in the third trimester compared to earlier pregnancy, while plasma concentrations remained unchanged. Urinary L-PGDS levels were significantly higher in early onset of preeclampsia (onset Conclusions Our results indicate the measurement of plasma and urinary concentrations of L-PGDS may be a potential diagnostic for preeclampsia. Disclosures J. Takeda: None. K. Kinoshita: None. K. Matsuoka: None. S. Takeda: None. Y. Eguchi: None. H. Oda: None. N. Eguchi: None. Y. Urade: None.