Human ovarian cancer cell lines, SKOV3 and its adriamycin-resistant substrain SKOV3/ADR and COC1 and its cisplatin-resistant substrain COC1/DDP, were subjected to acoustic exposure. The critical levels (LC), which resulted in no immediate cell killing, were determined in four cell lines, respectively. LC were the same in four cell lines. After being insonated by LC, cell proliferation and clone forming of SKOV3/ADR were suppressed but those of SKOV3 were not affected (1); cell reproduction of COC1 was triggered but that of COC1/DDP was not influenced (2); flow cytometry detected sub-G1 peaks in SKOV3/ADR and COC1/DDP (3). These findings suggested that there were differences in the responses to ultrasound exposure between chemosensitive and chemoresistant human ovarian cancer cells.