Prostate cancer remains one of the most common cancers in men and treatment options for patients with advanced or metastatic disease are limited. Immunotherapeutic approaches, such as passive or active immunotherapy, have been shown to be successful in treating some cancer patients. These rely on the identification of cancer specific antigens that can be targeted by the immune system or used to diagnose as early as possible and/or to monitor the disease and its progression. Several prostate cancer antigens have already been identified; these include Prostate-Specific Membrane Antigen (PSMA), Prostate Specific Antigen (PSA), Prostatic Acid Phosphatase (PAP), PAGE-4, PSP 94, differential display 3, prostate androgen-regulated transcript 1 and six-transmembrane epithelial antigen prostate-restricted antigens and these represent potential candidate for immunotherapy against prostate cancer. The following review describes the importance of these antigens with a particular emphasis to the PAP antigen and T21, a recently identified prostate cancer associated antigen, as very promising targets for prostate therapy.