Ovarian cancer is a leading cause of cancer mortality. Chemotherapy is effective in reducing tumor burden in a majority of patients, however, only approximately 20% of advanced disease patients will ultimately survive tumor free, and further treatment options are needed. Continuing advances in immunology make immunotherapy a promising area for future research. The design of immunotherapy strategies for ovarian cancer requires an understanding of the immune microenvironment of the peritoneal cavity, which is frequently involved with ovarian cancer metastases and is the site of its most devastating effects. Immunotherapy approaches for ovarian cancer include locoregional and systemic cytokine therapies, prophylactic and therapeutic vaccines, and adoptive immunotherapy strategies. This review will summarize previous clinical trials as well as future directions for research. Further progress in T-cell specific immune responses will require the identification of specific ovarian cancer antigens that are processed and presented on the surface of tumor cells in the context of specific HLA molecules. In addition, a more detailed understanding of functional relations between the peritoneal microenvironment and the metastatic process is required.