Ingestion of foreign bodies consist a quite common problem in the pediatric age group. Usually most of them traverse the gastrointestinal tract without complications and only in rare cases they get trapped within the appendix. This case report describes the ingestion of the tip of a mercury thermometer by a six-year-old girl. An elective appendicectomy was performed in order to avoid further complications. To the best of our knowledge, this is the first reported case of the tip of a thermometer within the appendix.