Aim: To identify possible risk factors for erectile dysfunction (ED) after transurethral resection of prostate (TURP) for benign prostatic hyperplasia (BPH). Methods: Between March 1999 and March 2004, 629 patients underwent TURP in our department for the treatment of symptomatic BPH. All patients underwent transrectal ultrasound examination. In addition, the flow rate, urine residue, International Prostate Symptom Score (IPSS) and quality of life (QOL) were recorded for those who presented without a catheter. Finally, the erectile function of the patient was evaluated according to the International Index of Erectile Function Instrument (IIEF-5) questionnaire. It was determined that ED existed where there was a total score of less than 21. The flow rate, IPSS and QOL assessment were performed at 3 and 6 months post-treatment. The IIEF-5 assessment was repeated at a 6-month follow-up. A logistic regression analysis was used to identify potential risk factors for ED. Results: At baseline, 522 (83 %) patients answered the IIEF-5 questionnaire. The mean patient age was (63.7 ± 9.7) years. The ED rate was 65 %. After 6 months, 459 (88 %) out of the 522 patients returned the IIEF questionnaire. The rest of the group was excluded from the statistical analysis. Six months after TURP, the rate of patients reporting ED increased to 77 %. Statistical analysis revealed that the only important factors associated with newly reported ED after TURP were diabetes mellitus (P= 0.003, r = 3.67) and observed intraoperative capsular perforation (P= 0.02, r = 1.12). Conclusion: The incidence of postoperative, newly reported ED after TURP was 12 %. Risk factors for its occurrence were diabetes mellitus and intraoperative capsular perforation.