The realization that prostate cancer is an immunogenic tumor, in conjunction with the discovery of novel methods for priming the immune system to generate an antitumor response, has resulted in several new approaches for prostate cancer immunotherapy. Based on these various approaches, several human clinical trials have begun using immune-based therapies for prostate cancer. These approaches can be divided into cytokine-based therapies, tumor-associated antigen-based therapies, tumor vaccines, and dendritic cell-based therapies. This review summarizes the latest findings from each of these approaches and gives results from the few completed human clinical trials.