Conventional cytotoxic chemotherapy fails to cure the majority of patients with advanced-stage ovarian cancer, in spite of encouraging initial antitumor responses. With the emergence of drug resistance in refractory tumors, new biologic and immunologic treatment strategies are needed. Small-volume residual peritoneal disease remains an attractive target for therapeutic trials; however, even in this optimal circumstance, few regimens have yet achieved a high frequency of pathologically confirmed complete remissions. Considerable progress has been made in understanding the impact of growth factors and their receptors on tumor growth regulation and modulation of response to chemotherapy. Better characterization of the antigens recognized by monoclonal antibodies, as well as sequencing of the antibodies themselves, has permitted the rational design of therapeutic reagents that take full advantage of molecular biology techniques for production and conjugation. Important limitations of preclinical models for prediction of host toxicity are recognized, and the reasons for treatment failure in situ, as well as strategies to prevent serious dose-limiting toxicities, are being explored. Further developments in cytokine biology, adoptive cellular therapy, monoclonal antibody conjugation, and molecular biology will continue to provide a growing array of reagents for critical evaluation.