We present an 11-year-old male child with an enormous appendix that was regarded as an appendiceal mucocele. The disorder is very rare and usually appears in middle aged patients. It is a clinical diagnosis. It could cause a variety of symptoms, especially, acute appendicitis and unidentified lesion in the right iliac fossa. According to the reasons, it could be just a curiosity without any relevancy or the sign of a malignant lesion with bad prognostic factors. The histopathological findings prove the origin.