We describe the derivation of three human ovarian carcinoma cell lines and the comparison of their properties with two previously described cell lines of like histology (SKOV-3 and CAOV-3). Two of the new lines (HOC-1 and HOC-7) were derived from separate ascites tumors (at 9-month intervals) of a patient with well-differentiated serous adenocarcinoma of the ovary. The third new line, HEY, was derived from a human ovarian cancer xenograft (HX-62) originally grown from a peritoneal deposit of a patient with moderately differentiated papillary cystadenocarcinoma of the ovary. The cell lines demonstrated differential ability to grow in semisolid culture and as xenografts in immunologically deprived CBA/CJ mice. Dose-response curves were generated for clonogenic cell survival of cells exposed to common chemotherapeutic agents; one of the lines (HEY) shows a degree of resistance to the alkylating agent cis-diamminedichloroplatinum(II) (cis-platinum). Common karyological features included structural abnormalities of chromosomes 3 and 11. Heterogeneity of expression of ovarian tumor-associated antigens was documented.