Lipocalin-type prostaglandin D synthase (L-PGDS) has recently been shown to be expressed in human brain tumors and breast tumors. However, L-PGDS expression has not been investigated in ovarian cancer. The objective of this study was to determine whether L-PGDS is expressed in human ovarian cancer. Lipocalin prostaglandin D synthase mRNA was cloned and sequenced by RT-PCR. Using in situ hybridization (ISH) technique, the expression of L-PGDS mRNA in 54 ovarian cancer was investigated. Expression of L-PGDS mRNA was found in tumor cells of all various types of ovarian cancers. Patterns of staining of tumor cells varied among different histological types of ovarian cancer. Significant discrepancy between the intensity of the staining and histological types of ovarian cancer could be established (p<0.01). It is reported for the first time that the expression of mRNA of L-PGDS exists in the ovarian cancer, and is related to the cancer type. This may have significance for the progress of ovarian cancer.