['We determined whether serial prostate needle biopsies predispose men to erectile dysfunction and/or lower urinary tract symptoms over time.', 'Men with prostate cancer on an active surveillance protocol were administered the 5-item Sexual Health Inventory for Men and International Prostate Symptom Score questionnaires on protocol entry, and at a cross-sectional point in 2008. All men had at least 1, 10 to 12-core prostate biopsy at protocol entry and yearly surveillance biopsies thereafter were recommended.', 'Of 333 men 231 returned the followup questionnaires. Correlations were found between biopsy number and erectile dysfunction, with increasing biopsy number associated with a decrease in Sexual Health Inventory for Men score (p = 0.04) and a history of 3 or more biopsies associated with a greater decrease in Sexual Health Inventory for Men score than after 2 or fewer biopsies (p = 0.02). Multivariable analysis for biopsy number, age, prostate volume and prostate specific antigen showed that only biopsy number was associated with decreasing Sexual Health Inventory for Men score (p = 0.02). When men were stratified by baseline Sexual Health Inventory for Men, those without preexisting erectile dysfunction (Sexual Health Inventory for Men score 22 to 25) trended toward steeper decreases in Sexual Health Inventory for Men score after 3 or more biopsies (p = 0.06) than did men with baseline mild to moderate erectile dysfunction (Sexual Health Inventory for Men score 8 to 21). No correlation was found between biopsy number and International Prostate Symptom Score.'] Are serial prostate biopsies associated with an increased risk of erectile dysfunction in men with prostate cancer on active surveillance?