Intravesical prostatic protrusion (IPP) is associated with increased urinary toxicities after radical prostatectomy. The aim of the current study is to investigate the effect of IPP on treatment outcomes and toxicity in prostate cancer patients who underwent definitive radiotherapy (RT). Medical records of 130 patients who received RT between April 2007 and October 2017 were retrospectively evaluated. All patients received conventionally-fractionated intensity-modulated RT to a total dose of 70-78Gy. We found a very strong positive correlation with MRI and CT thus IPP grades for the whole cohort were evaluated using CT scans. Acute toxicities were evaluated using CTCAE version4.0 and late toxicities were evaluated using RTOG/EORTC guidelines. Mann-Whitney U, chi-square and student-t tests were used for statistical analyses in SPSS version15.0. Forty-two patients did not have IPP, 19 patients had grade I, 47 patients had grade II and 22 patients had grade III IPP. There was no difference in age, PSA level and GS but prostate volume was higher in the IPP group (p= 0.013). With a median follow-up of 53.4 months, biochemical recurrences were observed in 10 patients in the IPP group and 2 patients in the non-IPP group (p= 0.334). There was no significant difference in treatment outcomes. RT was well tolerated however grade >= 2 acute genitourinary (GU) toxicity was higher in the IPP group (p=0.024). CT scan is strongly correlated with MRI in terms of grading IPP. IPP does not affect RT outcomes however it seems to be a risk factor for acute GU toxicity.