Prostate cancer is a significant health problem and one of the leading causes of cancer-related death among men. Given the typically long natural history of the disease, there is considerable interest in developing new therapies to treat or prevent metastatic disease, and cancer vaccines are a particularly attractive immune-based approach. Early clinical studies using non-specific immunomodulatory treatments have met with limited success, but also suggest that improved immunologic approaches might be useful in treating human prostate cancer. Over the last decade, the identification of immune cells responsible for actual destruction of prostate tissue and advances in immunologic and molecular techniques have led to a variety of vaccination approaches that are currently being evaluated in human clinical trials. The present article discusses the rationale in animal models for particular immunization strategies and describes the vaccines currently being used in patients with prostate cancer. The ongoing identification of tumor antigens and proteins involved in prostate cancer progression and the development of better immunologic animal models suggest a hopeful future for the design of effective prostate cancer vaccines.