The recent approval of Sipuleucel-T (Dendreon, Seattle, WA) from the Food and Drug Administration for the treatment of men with asymptomatic or minimally symptomatic castrate-resistant prostate cancer was a landmark in cancer immunotherapy, making this the first cancer "vaccine" approved for use in a treatment setting. This approval has led to renewed interest in cancer vaccines and to the recognition that prostate cancer represents an immunologically sensitive disease. At the current time, several vaccine approaches are under clinical investigation. These include viral vectors, antigen-loaded dendritic cells, and DNA vaccines. Each approach has its own set of advantages and disadvantages. This review will introduce the basic technology underlying these different vaccines and briefly discuss completed and ongoing clinical trials. As a great number of prostate cancer vaccines have been investigated in both preclinical and clinical settings, we will focus primarily on vaccines that are currently in clinical trials, as ascertained by a recent inquiry of the clinical trials database, www.clinicaltrials.gov.