A steadily growing number of studies have confirmed the beneficial effects of plant-derived substances (preparations) on the effectiveness of pharmacotherapy for ovarian cancer. A prior or parallel application of plant-derived substances and chemotherapy could be the way to strengthen the classic pharmacological treatment. Our paper presents several plant-derived substances with proven antiproliferative activities, in which phenolic and flavonoid bioactive compounds dominate, with particular emphasis on ovarian cancer cells. We are of the opinion that our paper will contribute to better understanding of the molecular basis for the positive interaction effect of concomitant application of the abovementioned plant substances with certain cytostatics. Also, this work may increase the number of preclinical in vivo experiments using these and other phenolic, flavonoid-rich plant substances to better understand their efficacy and safety and, in the future, to initiate clinical trials in this field.