In Vitro Colony Assay was carried out to examine chemosensitivity in 57 specimens from gynecologic malignancies, and following results were obtained. Total of 34 (59.6%) formed adequate colonies for sensitive assay. Among ten anticancer drugs that were tested, Cis-platinum, Adriamycin, 5-FU and Bleomycin were relatively effective for ovarian malignancies. In vivo chemosensitive tests were also performed using five xenograft systems of human gynecologic tumor. These in vivo results were compared with in vitro data, and a 75% true positive and an 87.5% true negative rate were observed. Retrospective correlations between in vitro chemosensitive data and patient responses to chemotherapy were analyzed from 15 evaluable patients, then a 71.5% true positive and a 75% true negative rate were observed. To obtain pharmacokinetic data on anticancer drugs, we measured concentrations of plasma and tumor tissue for Cis-platinum, Adriamycin and Bleomycin in operated patients and xenografts. The in vivo tissue concentrations were higher than the in vitro drug concentrations usually employed in colony assay. By comparing the inhibitory effects on tumor colony growth of 1-hr and continuous drug exposures in colony assay, in vitro continuous exposure schedules were made available for cell cycle specific anticancer drugs.