Prostate cancer is among the most common solid malignancies. A number of treatment alternatives exist for localized prostate cancer, including observation, prostatectomy, brachytherapy, and external-beam radiation therapy (EBRT). External-beam radiation therapy has changed dramatically during the past several years. Older techniques paved the way for 3-dimensional conformal radiation therapy (CRT), which in turn facilitated the introduction of intensity-modulated radiation therapy (IMRT). The prostate has served as a model disease site for the implementation of IMRT. As indicated by a growing body of experience, IMRT for prostate cancer represents a major technologic and clinical advance for radiation therapy. In this article, a review is provided of the evolution of EBRT leading to IMRT, the unique features making the prostate an ideal disease site for employing IMRT, the details of the clinical implementation of prostate IMRT and supporting technologic advancements, and the currently reported clinical outcomes of IMRT in prostate cancer. In addition, future directions of prostate IMRT, both technologic and clinical, are discussed.