Despite a global effort to significantly reduce mortality, ovarian cancer remains the fifth leading cause of cancer death among American women, and five-year survival rates remain discouragingly low at 45%. Novel therapies are urgently needed. Notably, higher infiltration of activated immune cells into the tumor microenvironment correlates with improved ovarian cancer survival, suggesting that promoting their activity could favorably impact clinical outcomes. Immunotherapy has recently demonstrated impressive clinical benefit in a variety of solid tumors. Immunotherapy strategies tested in ovarian cancer include vaccines, adoptive T cell therapy, and immune checkpoint blockade. Ultimately, a combination immunotherapy approach that integrates immunotherapy with other cancer treatment modalities in additive or synergistic ways will most effectively improve survival.