Contact with the tree processionary caterpillar or ingestion/inhalation of its airborne toxin-containing hairs and spines may cause a direct histamine-releasing or IgE-mediated allergic reaction in humans. The most common manifestations are urticaria and dermatitis; systemic manifestations such as respiratory involvement and anaphylaxis have been reported mainly in foresters. We describe a 12-year-old child who was presented to the emergency department with systemic allergic reaction (pruritic rash, conjunctival hyperemia, dyspnea, and wheezing), which eventually proved to be due to exposure to the pine tree processionary caterpillar. The diagnosis was made only after the child's repeated exposure to the caterpillar. Tree processionary caterpillar should be added to the list of causes of systemic allergic reactions in children, especially in endemic areas, and medical staff should be alerted the range of clinical manifestations to ensure prompt diagnosis and treatment.