Acute appendicitis is the most common acute surgical condition of the abdomen. Unfortunately, atypical presentations are common. Delayed diagnosis would therefore lead to higher morbidity and mortality. Furthermore, under estimation of an associated retro-peritoneal abscess can be disastrous. Our case illustrates the issues mentioned. A young lady presented with atypical symptoms of appendicitis but was diagnosed as perforated retrocaecal appendicitis with paranephric abscess following CT abdomen. An open appendectomy and drainage of retroperitoneal abscess were done with no drain inserted. Unfortunately four days later she developed a complete wound failure with surgical site infection. A diagnostic laparoscopy and drainage of retroperitoneal abscess was subsequently done. Post operatively, a total of 2000 mls of pus evacuated in 10 days. She recovered well and was discharged on post-operative day 14. Our case illustrates the atypical presentation of complicated retro-caecal appendicitis with retro-peritoneal (para-renal) abscess. A CT scan prior surgery is extremely beneficial in order to determine the best surgical approach and amount of retro-peritoneal abscess noted during an index surgery would be misleading. Therefore, a drain must always be inserted in order to avoid future morbidities.