Background: Hypofractionated radiotherapy (HypoRT) is increasingly being used to treat prostate cancer to take advantage of its likely low α/β ratio. There is limited experience in delivering a high biologically equivalent dose with HypoRT. We report long-term outcomes from patients treated with high-dose HypoRT. Methods: Patients with low and intermediate risk prostate cancer were treated using 3-dimensional conformal radiotherapy at a dose of 66Gy in 22 daily fractions of 3Gy without hormonal therapy. A uniform 7mm margin was created around the prostate for the planning target volume (PTV) and treatment was prescribed to the isocentre. Treatment was delivered using daily ultrasound image guided radiotherapy (IGRT). The CTCv3.0 was used to prospectively score toxicity. Biochemical failure was defined using the Phoenix criteria of nadir+2ng/ml. Results: A total of 129 patients were treated between November 2002 and December 2005. With a median follow-up of 90 months, the 5- and 8-year actuarial biochemical control rate was 97% and 92% respectively. The 5- and 8-year actuarial overall survival was 92% and 88% respectively. Only one patient died from prostate cancer at 92 months after treatment resulting in an 8-year actuarial cancer specific survival of 98%. Radiotherapy was well tolerated with 57% of patients experiencing no acute gastrointestinal (GI) or genitourinary (GU) toxicity. For late toxicity, the worst grade ≥2 rate for GI and GU toxicity was 27% and 33% respectively, but at the last follow-up the rate of grade ≥2 was only 1.5% for both GI and GU toxicity (Table). Conclusions: High dose HypoRT delivering 66 Gy in 22 fractions at 3Gy per fraction is a safe, effective and convenient modality of delivering radiotherapy to patients with favorable risk prostate cancer with excellent biochemical control rates and acceptable rates of acute and late GI and GU toxicity.