Pain in the right in iliac fossa can be a related to organ localized within this quadrant. The most appropriate clinical diagnosis for tenderness in Mc Burney’s point is acute appendicitis. An uncommon cause for pain in the right iliac fossa is endometriosis of appendix. We document a case of 45-year-old lady who presented with pain in the right iliac fossa pain and tenderness in Mc Burney’s point diagnosed clinically as acute appendicitis, which was surgically removed and confirmed by histopathological examination as endometriosis of appendix. This case highlights difficulty in making preoperative diagnosis in this uncommon entity and importance of specimen sampling and histomorphology of appendix for rendering the right diagnosis. In addition, differential diagnosis of endometriosis of appendix should be considered as one of the rare possibility in women particularly when pain is related to menstrual cycle.