Abstract: Ovarian cancer， one of the most malignant and lethal cancers of the female reproductive system，is an
extremely aggressive disease associated with a lack of early symptoms，rapid progression to peritoneal metastases，easily formation of drug resistance，which might be the main reasons resulting to poor prognosis for patients. One emerging model for the development of drug-resistant tumors invokes a pool of selfrenewing malignant progenitors known as cancer initiating cells（CICs），which has been paid much attention in recent years. It is possible to find a method to eradicate ovarian cancer by targeting CICs. CICS have been isolated successfully from ovarian cancer in current research，but more evidence is needed to confirm the definition of CICs.

Key words: Neoplastic stem cells, Ovarian neoplasms, Drug resistance, neoplasm, Antigens, CD44