81 Background: Dose-escalated radiotherapy for localised prostate cancer improves disease control but at the expense of increased overall treatment time and late toxicity. Given the low alpha-beta ratio for prostate cancer, treatment with hypofractionation should be biologically advantageous. Intensity-modulated radiotherapy (IMRT) allows dose escalation with hypofractionation, while achieving acceptable levels of toxicity. We report our 7 year late toxicity data in patients treated with two such regimens within the Hypofractionated Dose Escalation utilising Intensity-modulated Radiotherapy in Carcinoma of the Prostate (HIPRO) study. Methods: Sixty men, median age 75 years (50-87), with localised adenocarcinoma of prostate (T1-3NOMO) and either Gleason score ≥7 or PSA 20-50ng/L received 57Gy in 19 fractions (n=30) or 60Gy in 20 fractions (n=30) using 5-field inverse-planned IMRT. All patients received neoadjuvant hormone therapy, continuing for up to 6 months after treatment. Late toxicity was assessed at 7 years follow-up using RTOG criteria and LENT/SOMA questionnaire. Results: Forty-four (73%) patients were alive at 7 years. Nine patients (21%) reported RTOG grade 1 bowel or bladder toxicity; there was no grade 2 toxicity or above and no difference between the fractionation schedules. LENT/SOMA questionnaires were returned by 31/44 patients. Mean and median scores were less than one for bowel and urinary symptoms. When compared with pre-treatment, the proportion of patients with significant (maximum LENT/SOMA ≥2) urinary symptoms remained similar (75% vs. 76%), problems with sexual function had decreased (84% vs. 98%) but bowel symptoms increased (62% vs. 25%). At 5 years, overall survival was 83% and 74% and cause-specific survival was 83% and 84% in the 57Gy and 60Gy groups respectively. Conclusions: Dose-escalated hypofractionated IMRT for prostate cancer appears well tolerated with acceptable levels of late toxicity. Studies to assess long term disease control with these regimens are on-going. No significant financial relationships to disclose.