The 'Inguinal hernia' guideline was written over a period of two years by nine surgeons (including one epidemiologist) from all regions of the Netherlands with demonstrable clinical and scientific expertise in the area of inguinal surgery after a training course on 'The development of evidence-based guidelines'. A draft of the guideline was on the website of the Association of Surgeons of the Netherlands for a period of three months, during which time the members of the society could comment on its contents interactively. The guideline comprises chapters on risk factors and prevention, diagnostics, indications for treatment, treatment, day surgery, antibiotics, thrombosis prophylaxis, training, anaesthesia, postoperative pain control, complications, costs, aftercare, and specific aspects of inguinal hernia in children. For the treatment of adult patients a mesh technique is recommended. The Lichtenstein technique is recommended as the first choice for uncomplicated primary inguinal hernia. Laparo-endoscopic techniques can be used by trained teams for specific indications. Other techniques have not been compared with the current methods of treatment sufficiently. It is recommended that the operations be carried out in daycare and that the use of local anaesthesia should be considered more often. The diagnosis of inguinal hernia in a child is based on the physical examination. It is recommended that the surgeon should not rely solely on the history but confirm the presence of a hernia personally. The treatment of a paediatric inguinal hernia is always operative. Generally, the younger the child, the more urgent the operation because of the increased risk of incarceration in infants, particularly premature babies. There is no indication for routine exploration of the contralateral groin. If an incarcerated hernia cannot be reduced, emergency operation is necessary and referral to a paediatric surgical centre must be considered. The implementation and effectiveness of the guideline will be measured by taking an inventory of all inguinal hernia operations performed in the Netherlands before and after its publication.