Background: Inguinal hernia is one of the most common male diseases all over the world with an incidence rate of 18-24% throughout life. Chronic inguinal pain is one of the complications that prolong return to work time. Objectives: The main aim of this study was to determine the effect of ilioinguinal neurectomy on postoperative chronic pain (PCP) in patients that underwent open inguinal hernia repair via the Lichtenstein method. Materials and Methods: In this randomised controlled clinical trial, male patients with unilateral inguinal hernia were randomized into two groups: 74 cases in the preserved-nerve group and 66 cases in the nerve-excised group. The method of herniorrhaphy was the classic Lichtenstein method. Pain and numbness were evaluated at 1 day, 1 week, 1 month, 6 months and 1 year after surgery via visual analogue scale (VAS) system. We used SPSS ver.16 for analysis. Results: All patients were male with mean age of 39.1 years (with a range of 18 to 68 years). The follow-up rate was 100% after 1 year. Pain severity was significantly lower in nerve-excised patients at 1 day, 1week, 1 month and 6 months after surgery; but it was not significant after one year, although overall pain severity was low. Numbness was significantly higher in excised patients at all endpoints (1 day, 1month, 3 months, 6 months and one year after surgery). Conclusions: Ilioinguinal nerve excision at the time of inguinal hernia repair decreased post-surgical inguinal pain, and it can be used as a routine method in herniorrhaphy.