Abdominal wall endometriosis is a rare condition, which usually develops in a surgical scar of abdominal hysterectomy or Caesarean section. A 38-year-old lady presented in the surgical out patient department complaining of painful swelling in the lower abdomen, at the left edge of the scar of caesarean section. Computerized tomographic (CT) scanning of the pelvis with contrast revealed an enhancing mass in the abdominal wall extending from the skin to the muscle layer. A diagnosis of a tumour or an inflammatory mass was suggested and fine needle aspiration cytology (FNAC) of the lesion was advised to ascertain the nature of the lesion. The mass was removed completely and histopathology of the surgical specimen revealed endometriosis.