Background: Ant sting reactions are becoming an increasing problem in tropical countries. It is important for physicians to be aware of their possible cutaneous and systemic manifestations., Methods: A child with a severe allergic reaction to an ant sting was examined and is discussed. This is the first case described in the literature caused by the ant Odontomachus bauri, and the biology of the ant and the clinical signs in the patient are described., Results: A child developed a strong allergic reaction to an ant sting. The case was not associated with a previous ant sting. Treatment with the systemic antihistamine loratadine (Clarityn) was favorable in this patient., Conclusions: In tropical areas, ant stings are usually benign, self-limited pathologic processes. In some cases, however, severe allergic reactions can develop, including urticaria and anaphylactic shock. Physicians should be aware of the possible complications of ant stings.