INTRODUCTION: Curative treatments for localized prostate cancer, from least invasive to most invasive, include brachytherapy, cryosurgery, three-dimensional conformal radiation therapy, external beam radiation therapy, and radical prostatectomy. A patient with localized, low risk or intermediate risk prostate cancer who is diagnosed at an early age and receives one of these treatments has only an approximately 50% chance of maintaining an undetectable prostate-specific antigen (PSA) level, good spontaneous erections, and total continence by 5 years after treatment. OBJECTIVE: This article discusses transrectal high intensity focused ultrasound (HIFU) treatment of localized prostate cancer using the Sonablate 500 (Focus Surgery, Indianapolis, IN, USA) device, which the author has adopted in favor of the Ablatherm (EDAP, TMS S. A., Lyons, France) device, the other HIFU device approved for use in Canada. METHOD: Characteristics of the ideal prostate cancer include stage T1-T2b, less than 40 cc in size, and with an anterior-posterior dimension of up to 35 mm high. The anterior zone of the prostate is treated before the posterior zone. The procedure involves 2 to 3 second bursts of ultrasound energy, followed by 3 second cooling cycles. In each treatment lesion, the physician achieves a temperature of 100 C at the focal point. The device allows for real-time visualization of tissue response following the delivery of ultrasound energy. CONCLUSION: HIFU is a minimally invasive, outpatient treatment for localized prostate cancer that provides similar short term and medium term cure rates and considerably less morbidity and side effects than other treatments. Although the effectiveness of HIFU has not yet been demonstrated in large, long term studies, this treatment option should be discussed with patients who have just been diagnosed with low risk or intermediate risk prostate cancer and desire aggressive, noninvasive, curative therapy, with potentially a lower incidence of side effects compared to conventional therapy.