High Intensity Focused Ultrasound (HIFU) is a method of accurately delivering ablative ultrasound (US) generated high temperatures non−invasively or endo−luminally focused to specific areas in the body using imaging (ultrasound or MR) guidance. Intracavitary or endo−luminal (also called transrectal) HIFU has been appraised by the National Institute for Clinical Excellence (NICE) in the treatment of prostate cancer. It is currently used for primary prostate cancer; there is also evidence it may be effective in treating post-radiotherapy prostate cancer recurrence. Short and medium term data demonstrate that HIFU may be equivalent to some current prostate cancer therapies but with reduced morbidity and length of stay. As the prostate and rectum are adjacent there is now a natural evolution to translate the success in prostate to the adjacent rectum/other pelvic structures.