An appendectomy, also termed appendicectomy, is a surgical operation in which the vermiform appendix (a portion of the intestine) is removed. Appendectomy is normally performed as an urgent or emergency procedure to treat complicated acute appendicitis.

Appendectomy may be performed laparoscopically (as minimally invasive surgery) or as an open operation. Over the 2010s, surgical practice has increasingly moved towards routinely offering laparoscopic appendicectomy; for example in the United Kingdom over 95% of adult appendicectomies are planned as laparoscopic procedures. Laparoscopy is often used if the diagnosis is in doubt, or in order to leave a less visible surgical scar. Recovery may be slightly faster after laparoscopic surgery, although the laparoscopic procedure itself is more expensive and resource-intensive than open surgery and generally takes longer. Advanced pelvic sepsis occasionally requires a lower midline laparotomy.

Complicated (perforated) appendicitis should undergo prompt surgical intervention. There has been significant recent trial evidence that uncomplicated appendicitis can be treated with either antibiotics or appendicectomy. After appendicectomy the main difference in treatment is the length of time the antibiotics are administered. For uncomplicated appendicitis, antibiotics should be continued up to 24 hours post-operatively. For complicated appendicitis, antibiotics should be continued for anywhere between 3 and 7 days. An interval appendectomy is generally performed 6–8 weeks after conservative management with antibiotics for special cases, such as perforated appendicitis. Delay of appendectomy 24 hours after admission for symptoms of appendicitis has not shown to increase risk of perforation or other complications.