Introduction: Due to frequent diagnosis of ovarian cancer at an advanced clinical stage, in most cases surgical debulking is followed by chemotherapy. The principal cause of therapeutic failure involves incomplete surgery and resistance of neoplastic cells to chemotherapy. A search continues for substances which would overcome resistance to treatment and, as a result, would increase efficacy of the applied treatment. Quercetin represents one of more interesting compounds, which at present in subjected to several tests. Material and methods: Studies were performed on in vitro sensitivity of human ovarian cancer cell lines, SKOV-3, EFO27, OVCAR-3 and A2780P to low doses of quercetin and on the effect exerted by quercetin on sensitivity of the cell lines to cisplatin and pactitaxel. Results: The experiments proved that the studied cells of ovarian cancer manifest a similar sensitivity to quercetin. Following incubation of the cells with two distinct concentrations of quercetin and the studied cytostatic agents all the cells lines were found to significantly increase their sensitivity to pactitaxel In cases of two cell lines, OVCAR-2 and A2780P, they also significantly increased their sensitivity to cisplatin. Discussion: Our results demonstrated suitability of low quercetin doses (achievable using oral administration) as a substance which increases sensitivity of ovarian cancer cells to cisplatin and paclitaxel. The value of quercetin include its wide accessibility, efficacy and a broad range of activity but also its low toxicity, as compared to other examined compounds. Conclusions: Used in low doses, quercetin increases chemosensitivity of ovarian cancer cells.