Treatment options for prostate cancer are currently widely discussed in the media and by urologic associations. International studies showed that current treatment options may significantly affect the quality of life (including incontinence and erectile dysfunction) while only offering marginal survival benefits. Low to medium risk patients in particular don't seem to be ideal candidates for radical treatment by surgery of radio therapy. For this large group of patients focal therapy offers additional valuable treatment option. Malignant prostate tissue can be specifically ablated by High-Intensity Focused Ultrasound (HIFU). Thus, the cancer can be controlled without removing the whole prostate and with minimal side effects. Multimodal magnetic resonance tomography, specific biopsies and monitoring contribute to the safety of this new treatment strategy.