Background Hypersensitivity reactions (HSR) to biologic drugs (BD) may limit their use in children with rheumatic diseases. We aimed to analyze the incidence and clinical characteristics of immediate type I (IgE/non-IgE) hypersensitivity reactions to BD and the risk factors for these reactions. Methods Children with rheumatic diseases using BD who were evaluated in the pediatric allergy department for possible drug hypersensitivity reaction (DHR) due to BD or any other drug were included in the study. Results One hundred and twenty-eight children (49.2% boys; 14.6 years [9.9-16.9 years] with juvenile idiopathic arthritis [58%], familial Mediterranean fever [14%], vasculitis [14%], and other diseases [14%]) had used eight different BD with 32 494 infusions/injections. Fifteen patients were evaluated for DHR [injection-site reactions [n = 4], adverse events [n = 2], drug hypersensitivity other than BD [n = 3], and immediate BD hypersensitivity [n = 6]). The incidence of immediate BD HSR was 4.7%, with a clinical presentation of anaphylaxis in 3.9% (tocilizumab [n = 3], rituximab [n = 2], positive skin test with culprit BD [n = 3]). Among patients with BD HSR, the median follow-up was longer (84.5 vs 54 months, P = .048), and renal (33.3% vs 4.1%, P = .002), hematologic involvement (16.7% vs 0, P < .001), and active disease (83.3% vs 13.9%, P < .001) were more common. Logistic regression analysis revealed that renal involvement, more than 14 hospitalizations per lifetime, and more than two different BD used were associated with BD hypersensitivity. Conclusion The frequency of severe immediate HSR due to BD was shown to be 3.9% in children with rheumatic diseases. Children with active rheumatic disease and who have exposure to multiple BD should be monitored for BD HSR, particularly during intravenous BD infusions.