Objective: To investigate whether GnRH-agonist (GnRH-Ag) using in IVF-ET affects apoptosis of human granulosa-luteal cells and expression of peripheral benzodiazepine receptor (PBR) protein involved in the apoptosis of the cells. Methods: Granulosa-luteal cells obtained during oocyte retrieval were cultured and treated with $10^{-5}M$ GnRH-Ag. Apoptosis of the cells by the treatment was confirmed using DNA fragmentation analysis 24 h after culture. The presence of PBR protein within the cells was examined by immunofluorescence staining and the expression of the protein was analyzed by Western blotting. In addition, it was measured for progesterone and nitric oxide (NO) produced by granulosa-luteal cells after GnRH-Ag treatment. To evaluate the relationship between NO production and PBR expression, sodium nitroprusside (SNP) as a NO donor was added in media and investigated the expression of PBR protein by Western blotting. Results: Apoptosis increased in the granulosa-luteal cells 24 h after GnRH-Ag treatment, whereas the expression of PBR protein significantly decreased. Furthermore, the production of progesterone and nitric oxide (NO) by the cells significantly fell from 12 h after the treatment. In the results of Western blotting after SNP treatment, the expression of PBR protein increased in the treatment with SNP alone to the granulosa-luteal cells, but was suppressed in the treatment with GnRH-Ag and SNP. Additionally, the staining result of PBR protein in the cells showed the even distribution of it through the cell. Conclusion: These results demonstrate that GnRH-Ag treatment induces apoptosis, decreasing expression of PBR protein and NO production in human granulosa-luteal cells. The present study suggests that one of the apoptosis mechanism of human granulosa-luteal cells by GnRH-Ag might be a signal transduction pathway via NO and PBR.