The purpose of a new study published in The Journal of Allergy and Clinical Immunology. In Practice was to delineate the causal relation between gastroesophageal reflux disease (GERD) and asthma. The present study enrolled participants of the Korean National Health Insurance Service-National Sample Cohort 2002-2013, who were ≥ 20 years old. In the first study, 116502 GERD patients were matched in the 1:2 ratio to 233004 control (I) participants, and the hazard ratio (HR) of asthma in GERD patients was analyzed. In the second study, 104146 asthma patients were matched in a 1:1 ratio to an equal number of control (II) participants, and the HR for GERD in asthma patients was analyzed. The findings revealed that in the first study, 12.5% among the GERD group and 7.8% from the control (I) group presented asthma. The GERD group demonstrated a 1.46-fold higher HR for asthma than the control (I) group. Whereas, in the second study, 16.9% from the asthma group and 11.9% from the control (II) group presented GERD—indicating a 1.36-fold higher HR for GERD than the control (II) group. All age and sex subgroups presented consistent results. Therefore, it was concluded that GERD and asthma had a bidirectional relation in the study population.