The aim of our study was to investigate the lymphocytic infiltration rate of ovarian tumors and the possible use of tumor-infiltrating lymphocytes (TIL) as a therapeutic tool in gynecologic oncology. Twelve tumors were treated with digesting enzymes in order to isolate tumor-infiltrating lymphocytes as well as tumor cells, TIL were expanded by culture in the presence of human interleukin-2 (IL-2). Freshly prepared tumor cells were allowed to grow in culture medium for several days before the first investigations were performed. TIL could only be isolated from 50% of the investigated tumors. In contrast to this the isolated tumor cells could be largely expanded in 73% of the cases. The expression of the CA125 antigen in the culture supernatants served as control and could still be evaluated up to three months after isolation. In parallel the antigen expression on the cellular surface was estimated by immunocytochemistry. Evaluating the phenotypes of TIL showed predominantly CD³⁺, their expansion rate was only poor. Tumor cells were isolated and expanded in order to test the tumor-directed cytotoxic efficacy of TIL and for further use in transplantation to nude mice.