The effectiveness of the treatment of advanced ovarian cancer depends on its proper qualification based on clinical assessment, imaging and biochemical studies. However, due to the dissemination of the disease, the methods given above often turn out to be insufficient. Intraoperative, quantitative assessment of the stage of the cancer, conducted with the use of the peritoneal carcinomatosis index developed by Sugarbaker, consisting in awarding points dependent on the location and the size of cancerous lesions in the peritoneal cavity, allows for precise estimation of the possibility of debulking surgery. It has to be kept in mind that in cases of advanced ovarian cancer surgical treatment is a multiorgan procedure, requiring the participation of a team of highly skilled gynecologists and oncological surgeons. Numerous studies have demonstrated the superiority of surgical treatment performed by competent and experienced teams – the result of their work is the optimal reduction in the size of the tumor, which is reflected by the length of time before the recurrence of the disease and the time of patient survival. Suboptimal treatments, on the other hand, caused, among others, by inadequate pre- and intraoperative assessment of the progress of the disease, significantly worsen the results. Determining the feasibility and the degree of the resection of the tumor allows to make a decision about the adequate treatment, that is, the primary or secondary surgery. It is well known, after all, that lack of possibility to achieve at least the optimal cytoreduction is an indication for neoadjuvant chemotherapy. An objective assessment of the extent of the disease by calculating the peritoneal carcinomatosis index can therefore be crucial in the treatment of advanced ovarian cancer.