Two cell lines, Kuramochi and CKS, established from human ovarian cancer, were analyzed in vitro drug sensitivity to Mitomycin C and Carboquone. These values were compared to those of eight human gastric cancer cell lines composed of various histological types. The CKS cell line, derived from serious cystadenocarcinoma, was less sensitive to both test-drugs than the groups of gastric cancer cell lines. Therapeutic indices of the two drugs were very low. So it was considered that the two drugs were unsuitable to chemotherapy to serous cystadenocarcinoma. The Kuramochi cell line, derived from undifferentiated carcinoma, was less sensitive to Mitomycin C than the groups of gastric cancer cell line. However, it was as sensitive to Carboquone as high-sensitive gastric cancer cell lines. Therapeutic index of the Carboquone in the undifferentiated carcinoma was high. So it was considered that Carboquone was suitable to chemotherapy to undifferentiated adenocarcinoma. The cytocydal actions of the two drugs were dependent upon dose and time. Time-dependency was, however, smaller in Carboquone than in Mitomycin C.