The incidence of appendicectomy is high in France and this operation is performed in 15 to 45% of the cases for a histologically normal appendix. White blood cell count has a very good sensitivity but a bad specificity. The same observation goes for plain abdominal X-rays, the use of while must be limited in children and young women. Barium enema, frequently performed in anglo-saxon countries, show in 90 to 100% of the cases an abnormal image of the caecum or a lack of visualisation of the appendix. Ultrasounds visualize the appendix with a good sensitivity, provided there is no perforation. Laparoscopy is a good diagnostic tool, but must not be considered as a routine procedure. Studies of diagnosis scores show that, except for the white blood cell count, biological and radiological investigations are particularly interesting to eliminate another pathology.