Background:Mycoplasma infection is sporadic and continues to occur every three to four years. Even macrolide has been used as a drug of choice at pediatric mycoplasma infection, resistance of macrolide tends to increase. The purpose of this study is to determine if IVIG is effective in patients with mycoplasma infection in case they are co-infected with respiratory virus. Methods:We studied 216 children who had been admitted to the pediatric department in Wonkwang University Hospital for mycoplasma infection and underwent macrolide therapy for fever for more than 2 days after admission, from January 2013 to December 2016. The patients of Mycoplasma infection were divided into two groups; group A (106 patients) without respiratory virus infection and group B (110 patients) with respiratory virus infection. Group A was divided into two subgroups which are a group with use of macrolide alone (group A1) and a group with use of macrolide and IVIG (group A2). Also group B was divided into two groups which are a group with use of macrolide alone (group B1) and a group with use of macrolide and IVIG (group B2). We compared fever duration for each group. Levels of hemoglobin, white blood cell count, erythrocyte sedimentation rate, CRP were also studied. Results:When comparing group A and B, the fever duration was longer in group B (6.4±1.3 days) than in group A (4.4±1.6 days, P 0.05). When the fever duration was compared within group A, the fever duration was longer in group A2 (27 patients, 5.3±2.09 days) than group A1 (79 patients, 4.1±1.4 days, P 0.05). When the fever duration was compared in Group B, it was shorter in group B2 (22 patients, 5.4±1.7 days) than in group B1 (88 patients, 6.6±1.0 days, P 0.05). WBC count was higher in group B (11903±5527/ug) than group A (8932±4779/ug, P 0.02), and there were no other laboratory findings showing any significant differences. Conclusion : The fever duration was found to be longer in a group of mycoplasma infection with respiratory viral co-infection than a group of mycoplasma infection alone. In the absence of respiratory viral co-infection, simultaneous use of macrolide and IVIG had no effectiveness at reducing fever duration. However, simultaneous use of macrolide and IVIG in the group of mycoplasma infection with respiratory viral co-infection was effective in reducing the fever duration.