As the prevalence and socioeconomic burden of allergic rhinitis is steadily increasing every year, it is essential that clinical practitioners diagnose and manage allergic rhinitis in an evidence-based manner. Therefore, the Korean Academy of Asthma, Allergy and Clinical Immunology developed new clinical guidelines for Korean patients and practitioners. We first performed a questionnaire survey to address the core questions, about which clinical practitioners are the most curious. A large group of physicians (allergists), pediatricians, and otorhinolaryngologists developed answers for those questions by performing a systematic literature review and determining the appropriate levels of recommendation. In this article, we propose 11 answers for core questions regarding the diagnosis and differential diagnosis of allergic rhinitis.