PURPOSE: Urticaria is a common disorder, with a lifetime incidence of approximately 15%–20% of the general population. It is difficult to differentiate urticaria in children because of the similarity in symptoms between acute and chronic urticaria. There is also a lack of studies between vitamin D known as an important role in the immune system and urticaria in children. The present study aimed to assess the characteristics and allergen sensitization of young children diagnosed with urticaria and to evaluate the relationship between their vitamin D status and urticaria. METHODS: We retrospectively reviewed medical records of 218 children diagnosed as having urticaria at CHA and Myongji Hospitals between April 2013 and December 2014. The results of questionnaires and laboratory tests, including specific IgE and serum 25-hydroxy vitamin D concentrations were obtained. RESULTS: Of 218 patients, 118 (54%) were positive for at least 1 allergen and there was no significant difference in the prevalence of sensitization between the acute and chronic urticaria groups. However, the prevalence of polysensitization and sensitization of house dust mites was significantly higher in the chronic urticaria group than in the acute urticaria group (P=0.011 and P=0.029, respectively). Among the urticaria symptoms, an itching sensation was more associated with insufficient vitamin D status in children with urticaria (P=0.034). CONCLUSION: Our results demonstrated that children with chronic urticaria have a higher prevalence of sensitization to house dust mites and polysensitization. Further studies will need to determine whether the supply of vitamin D can improve itching sensation in urticaria children with an insufficient vitamin D status.