BACKGROUND Some cases of left-sided appendicitis related to malrotation or situs inversus have been reported. Another type of left-sided appendicitis is reported. METHODS A 9 year-old boy was admitted suffering from a 2-day history of severe left-sided abdominal pain of the lower quadrant with fever at 38 degrees C. He presented abdominal tenderness and guarding, maximal in the left lower quadrant. His leukocyte count was 22,000/mm3. Ultrasonography showed a digestive tubular structure with thick walls in the left lower quadrant. CT scan revealed a dilated right-sided appendix with localized perforation, whose extremity was located in the left lower quadrant along the lateral wall. The diagnosis was confirmed by median laparotomy. CONCLUSIONS Left-sided appendicitis can also be related to a dilated right appendix with its extremity in the left lower-quadrant near the lateral wall. CT scan can then be helpful for diagnosis when ultrasonography remains unconclusive.