Circulating tumor cells (CTCs) are cells released from the primary tumor and circulating in peripheral blood. CTCs are an important element in the process of understanding the biology of metastases. In the future CTCs may be used as biomarkers for the assessment of neoplastic process progression and recurrence. The CTCs presence in peripheral blood was described in various tumors, and the possibility of their use in clinical procedures was demonstrated. The appearance of CTCs is a sign of metastasis formation and its spread via the circulatory system. Ovarian cancer is a special type of tumor as it grows and recurs mainly in the abdominal cavity. Despite advances in therapeutic methods, more than half of the patients with ovarian cancer experience disease recurrence which cannot be cured. Therefore, it is important to seek better treatment strategies for patients with advanced disease. There is evidence that CTCs in patients with ovarian cancer may be associated with the appearance of recurrences, disease-free time and total survival time. Detection and molecular analysis of CTCs may also be a non-invasive test for detecting an early stage of the disease, impossible to diagnose using currently available diagnostic tools. Monitoring can also be a prognostic factor enabling the evaluation of the therapeutic response. CTCs detection will contribute to better patient outcomes by using an improved system of diagnosis and monitoring of patient therapy, allowing for immediate implementation or change of the treatment when necessary.