Induction of apoptosis in target cells is a key mechanism by which chemotherapy induces cell killing. An in vitro system has been established for determining carboplatin and paclitaxel (Taxol) chemosensitivity of epithelial ovarian cancer cells, where measurements of caspase-3 activation are surrogate markers for activation of chemotherapy-induced programmed cell death. To validate the assay as a predictor of clinical chemotherapy-induced programmed cell death. To validate the assay as a predictor of clinical chemosensitivity in vitro apoptotic response were compared to the clinical response of the patients from whom the tumor cells were isolated. Caspase-3 activation in response to in vitro chemotherapy to both drugs was shown to have an 83% positive predictive value and a 71% negative predictive value. Markers of apoptosis such as caspase-3 activation can be quantitated and utilized to predict the clinical response to chemotherapy.