There is a growing interest in the use of proton therapy for the treatment of many cancers. With its unique dose-distribution properties, proton therapy has the potential to improve the therapeutic ratio of prostate radiation by allowing for an increase in dose without a substantial increase in side effects. While much evidence supports this notion in the context of many oncologic sites, only limited clinical data have compared protons to photons in prostate cancer. Therefore, the increasing enthusiasm for the use of protons in prostate cancer has aroused considerable concern. Some have questioned its ability to limit morbidity, and others have questioned its value relative to the cost. In addition, theoretical concerns have been raised about a potential additional risk for secondary malignancies. In this article, we review the current status of the evidence supporting the use of protons in prostate cancer and discuss the active controversies that surround this modality.