HIFU (High Intensity Focused Ultrasound) is an emerging new therapy which uses intense heat applied through the rectum to destroy the prostate and the contained prostate cancer.. It is extremely useful in older patients who are unsuitable for surgery or radiotherapy or who refuse surgery or radiotherapy and particularly suits patients who have had a previous TURP. Furthermore, it is one of the only therapies that can be used after radiotherapy has failed. High Intensity Focused Ultrasound initially causes difficulty in passing urine with frequency and burning and some risk of infection and temporary incontinence, but by three months, most of these symptoms have disappeared. Sexual side-effects depend on the extent of the treatment.