Recent studies have demonstrated that apoptotic cell death plays an important role in the mechanism underlying follicular atresia and luteolysis. However, the mechanisms responsible for initiating these processes have not been elucidated. In in vitro fertilization (IVF) programs, it is highly possible that continuous and repeated administration of FSH/hMG and GnRH agonists for the usage of ovarian hyperstimulation may induce apoptotic death of granulosa cells leading to atresia in the human ovarian follicles. The present study was performed to investigate whether FSH/hMG and GnRh agonists used for a longer period in controlled ovarian hyperstimulation has any effect on the apoptosis of granulosa-luteal (GL) cells obtained from hyperstimulated ovaries. To examine apoptotic cell death in the GL cells, cells were stained with acridie orange followed by observed in some of GL cells. Similar but distinct staining of apoptotic GL cells was observed when the cells were examined by using in situ TUNEL method. The healthy-looking cells with normal nuclear morphology were not stained, whereas cells with pyknotic nuclei or with apoptotic nuclei were intensively stained. After examining the ultrastructural features of GL cells by TEM, it was confirmed that the majority of cells seemed to have normal nuclei while GL cells undergoing apoptotic cel death were rarely found. The DNA extracted from GL cells showed a typical pattern of fragmentation following DNA electrophoretic analysis. We have confirmed that the apoptosis occurs in granulosa-luteal cells obtained from hyperstimulated ovaries. Technically, in situ apoptosis detection method is simple and reproducible and is well suited to identify the quality of oocytes retrieved from hyperstimulated ovaries.