Despite the recent improvement in the treatment of ovarian cancer, this disease is still leading cause of cancer death in women. In this study, the anti-tumor activity of cytokine-induced killer (CIK) cells against human ovarian cancer was evaluated in vitro and in vivo. Although CD3+CD56+ cells were rare in fresh human peripheral blood mononuclear cells, they could expand more than 1,000-fold on day 14 in the presence of anti-CD3 antibody plus IL-2. At an effector-target cell ratio of 30:1, CIK cells destroyed 45% of SK-OV-3 human ovarian cancer cells, which was determined by the 51Cr-release assay. In addition, CIK cells at a dose of 23 million cells per mouse inhibited 73% of SK-OV-3 tumor growth in nude mouse xenograft assay. This study suggests that CIK cells may be used as an adoptive immunotherapy for patients with ovarian cancer.