Proton beam therapy (PBT) has been in use for a number of decades, though interest in PBT for localized prostate cancer has grown substantially in recent years. Protons offer the theoretical potential of achieving dose escalation and decreasing toxicity by capitalizing on unique physical dose deposition characteristics to avoid normal tissue. Although it has proven effective in a number of malignancies including as a means for dose escalation in prostate cancer, there is little published clinical data to support its comparative superiority over alternative forms of conformal radiation for prostate cancer. This review article explores the current evidence and clinical experience supporting PBT for prostate cancer, the uncertainties and controversies associated with this innovative technology, its potential economic implications, and future promise.