By surgeon’s perspective, complicated appendicitis is defined as perforated appendicitis, periappendicular abscess, gangrenous appendicitis or peritonitis, noted on radiological studies upon hospital admission, operative reports or pathology results of the surgical specimen. Despite that this clinical condition is truly common in everyday surgical routine, its causes and risk factors are still unclear. Some parameters have been associated with complicated appendicitis, like older age, type 2 diabetes, symptoms for longer duration, appendicoliths/fecaliths, delays in surgery after onset of symptoms and after admission. Furthermore, currently, there is no standard diagnostic algorithm for complicated appendicitis. To be specific, radiological findings lack sensitivity, intraoperative assessment may overestimate it while, histopathological examination is regarded as more specific diagnostic method. In addition, the optimal treatment for complicated appendicitis remains controversial between an immediate surgical operation (laparotomy/laparoscopy) or a trial of nonoperative management. Hereby, by reviewing the current literature, we would aim to clarify the risk factors and the diagnostic procedure of complicated appendicitis as well as to compare the operative management with the conservative one according to the type of complicated appendicitis, the success rate and the postoperative complications.