Acute appendicitis (AA) is one of the most common causes of acute abdominal pain, which can progress to perforation of the appendix and peritonitis. Recently, AA has been classified into uncomplicated (nonperforated, no phlegmon) or complicated (abscess, perforation, phlegmon) appendicitis, for an appropriate initial treatment. With respect to surgical treatment of AA, laparoscopic surgery has been widely accepted worldwide as a safe and feasible first-line treatment. Over the last decade, non-operative treatment has been proposed as an alternative to surgery in uncomplicated AA, and has also played an important role in the management of complicated AA. AA is also the most common cause for abdominal surgery during pregnancy, though an accurate diagnosis of AA during pregnancy is challenging. In this review, the topics being discussed include: 1) Non-operative management for uncomplicated AA, 2) Management for AA in pregnancy, 3) Management for complicated appendicitis (especially immediate laparoscopic surgery for appendiceal abscess), 4) Appendiceal neoplasms related to complicated AA.