The aim of this thesis is the endoscopic TEP hernia repair, which is an appealing technique for patients with inguinal hernias. TEP, offering an adequate intraoperative diagnosis and subsequent treatment of all hernia subtypes is in experienced hands associated with low recurrence rates and rates of (chronic) postoperative pain. The supposedly substantial learning curve remains its most important disadvantage, emphasizing the need to have TEP performed by experienced surgeons. Limited and conflicting data are available on the extent of the learning curve. In Chapter 2 of this thesis, the relation between (surgeon) expertise and operative time, perioperative complications, conversion rate and recurrences was studied, in order to define the end of the learning curve of TEP. It was observed that during the first 50-100 TEP repairs, outcomes optimized in terms of intraoperative complications and recurrences, while a decline in the conversion rate, incidence of short-term postoperative complications and operative time was still observed after more than 400 individually performed TEP procedures. In addition, the overall perioperative complication rate and the incidence of chornic pain compared favorably to these outcomes reported by others. Since the setting of this thesis is a high volume TEP clinic, these outcomes also imply relevance of “concentration of care”. During the learning curve of TEP, the risk of serious complications is higher and operative times are longer. Perioperative difficulties encountered during this period may be reason for the surgeon to abandon this operative technique. In Chapter 3, patient- and hernia related characteristics associated with perioperative complications and operative time were studied. It was observed that the surgeon gaining experience with TEP repair should select young and slender male patients with a unilateral inguinal hernia and no previous abdominal surgery, in order to best overcome the learning curve. In Chapter 4 the outcomes of TEP hernia repair in a subset of female patients were studied. It showed that femoral hernias are very common in women, but that preoperative diagnosis of the correct hernia type is difficult. A TEP repair offers the opportunity to diagnose all hernia types intraoperatively and to treat them appropriately with excellent outcomes. The second part of this thesis focuses on several longterm outcomes after TEP. Reported incidences of debilitating chronic pain vary between 2-5% after endoscopic hernia repair, hence significantly lower compared to pain rates of 11-21% after conventional open hernia repair. Chapter 5 describes pain after TEP being selflimiting within the first postoperative year, with only 1% of the patients reporting substantial pain. The incidence of impaired sexual function due to pain also decreased from to 1% postoperatively. Male fertility is supposedly at risk in patients undergoing hernia repair. This might be due to vascular injury or iatrogenic damage/scarring of the vas deferens. In the review described in Chapter 7, several animal models show sustantial effects of hernia surgery on the structures in the spermatic cord. Clinical studies, however, indicate that this impact is limited. Future studies are needed to further investigate the clinical relevance of (endoscopic) hernia repair on male fertility.