Programmed cell death 5 (PDCD5) is a novel apoptosis-promoting protein. Although the decreased expression of PDCD5 has been recently found in a few types of human tumors, the status and significance of PDCD5 in ovarian cancer has not been evaluated. In the present study, we detected PDCD5 expression in 20 normal human ovaries and 26 serous cystadenomas and 41 serous cystadenocarcinomas by RT-PCR, Western blotting and immunohistochemistry, and analyzed the relationship between PDCD5 expression and clinicopathological data or patient survival. PDCD5 was expressed in all normal ovaries and serous cystadenomas, 80% (16/20) of normal ovarian tissues and 76.9% (20/26) of serous cystadenomas with moderate or strong PDCD5 protein expression. In contrast, 22% (9/41) of serous cystadenocarcinomas had no detectable PDCD5 protein expression and 46.3% (19/41) exhibited weak PDCD5 expression. The overall expression of PDCD5 in serous cystadenocarcinoma was significantly lower compared with normal ovarian tissues or serous cystadenomas (p<0.01). Furthermore, lost or decreased PDCD5 expression in serous cystadenocarcinomas was associated significantly with FIGO stage (p<0.05) and poorer disease-specific survival of patients (p<0.05). In conclusion, our data suggest that lost or reduced PDCD5 expression may contribute to the pathogenesis of human serous cystadenocarcinomas.