Background. Papular Urticaria (PU) is a cutaneous hypersensitivity disorder triggered by hematophagous arthropod bites. Despite being a common condition, especially in tropical environments, many knowledge gaps are observed for this disease. The main objective of this study was to investigate the patterns of humoral immune response to mosquito antigens in children with PU and establish a correlation between this response and the severity of clinical symptoms. Methods. An analytical cross-sectional observational study was carried out. Clinical and sociodemographic data and children’s blood samples were collected to measure the specific antibodies from: 1. A. aegypti salivary gland antigens; 2. A. aegypti whole body antigens (both produced in the laboratory of the Center for Health Sciences at the Federal University of Rio de Janeiro). A PU severity score based on clinical data is proposed to correlate disease severity with antibody reactivity signatures. Results. According to the clinical data, 58.9% of children received high severity scores. A significant statistical correlation was found between patients with high PU severity score and the development of symptoms before the age of two (p = 0.0326) and high IgG4 anti-salivary gland antigens concentration (p < 0.05). Conclusion. It is suggested that PU severity in children is associated with a high concentration of IgG4 anti-salivary gland antigens from Aedes aegypti. Further studies are recommended to deepen the understanding of the mechanisms involved.