Background. Ovarian cancer has the highest mortality rate of gynaecological cancers. This is partly due to the lack of effective screening markers. Indices of oxidative stress are well-recognized prognostic criteria for tumorous transformation of tissue, but their value depends on the type of tumor and the stage of its development. Objective. The aim of this study is to clarify the relationship between antioxidant/pro-oxidant ratio and the signs of molecular lesions and apoptosis rate in blood of ovarian cancer patients and non-cancer ones. Results. The ovarian cancer group is marked by antioxidant/prooxidant balance shifting to oxidative damage in blood as the consequence of overexpression of oxyradicals (by 300%). Higher level of glutathione (by 366%), lower level of metallothioneins (by 65%) as well as higher level of lipid peroxidation (by 174%) and protein carbonyls (by 186%) in blood of ovarian cancer patients compared to the normal ovarian group have been observed. The signs of cytotoxicity are determined in blood of ovarian cancer patients: an increased (compared to control) level of DNA fragmentation (by 160%), choline esterase (up to twice), higher rate of both caspase dependent and caspase independent lysosomal mediated apoptosis. Conclusions. Cathepsin D activity both total and free, choline esterase activity, TBA-reactive substance and protein carbonyls level in blood could be used as the predictive markers of worse prognosis and the signs of human ovarian cancer.