Three human cancer cell lines (OC 314, OC 315, and OC 316) were newly established in permanent culture from the ascites of patients with serous adenocarcinoma of the ovary. OC 314 was derived from an untreated tumor presenting with ascites at diagnosis; OC 315 was isolated from a neoplasm progressing after cisplatin-containing regimen; and OC 316 was collected from a patient with pleural metastasis at diagnosis, resistant to different chemotherapeutic treatments including Taxol. These cell lines were repetitively subcultured once to twice a week through 75-80 passage generations. Tumor cells grew as monolayers and displayed epithelial-like morphology, consistent with a feature of adenocarcinoma, which was then confirmed by the expressions of cytokeratins and vimentin. The cell lines proved highly tumorigenic when transplanted into nude mice, both subcutaneously and intraperitoneally. In addition, the mice inoculated with subcutaneous OC 316 developed extremely aggressive tumor, also invading the peritoneum, which correlated with the malignant behavior of the original tumor. Drug sensitivity, evaluated by the MTT assay, showed that the three cell lines expressed similar sensitivity to doxorubicin. Responses to cisplatin essentially reported low sensitivity of OC 314 and OC 315 and resistance of OC 316, thus reflecting the original sensitivity at the clinical level.