Failure in ovarian cancer therapy, following cytoreduction and chemotherapy, is related to the presence of cancer stem cells - a small subpopulation of cells resistant to chemotherapy and irradiation - in the tumour which may cause cancer relapse and manifestation of metastases. Therapies targeted at Cancer Stem Cells (CSCs), such as those employing metformin (a drug used in the treatment of diabetes type II) and salinomycin, an antibiotic isolated from Streptococcus albus bacteria, seem promising. Anti-angiogenic therapy with bevacizumab was found to be effective in all phases of ovarian cancer treatment. The presence of CSCs has been associated with angiogenesis. Several CSC biomarkers correlate with the markers of angiogenesis and some signalling pathways, e.g. Notch, and are used by both CSCs and by pro-angiogenic factors.