Purpose: This study was conducted to compare clinical features between Mycoplasma pneumonia and viral pneumonia. Methods: We retrospectively analyzed the medical records of 428 patients requiring hospitalization among children younger than 18 years of age in 5 hospitals in Seoul and Gyeonggi-do. There were 131 patients with M. pneumonia and virus coinfection, 167 patients with M. pneumonia without virus coinfection, and 130 patients with viral pneumonia. All subjects had radiographic evidence of pneumonia with specimens available for both M. pneumonia and viral testing. Virus was identified using the polymerase chain reaction assay in a nasopharyngeal or oropharyngeal swab. M. pneumoniae pneumonia was diagnosed serologically. Results: Human rhinovirus was detected in 60.3% (79 of 131) of children with M. pneumonia accompanied by virus coinfection. Respiratory syncytial virus (RSV) was detected in 38.2% (50 of 130) of children with viral pneumonia. The mean age was significantly lower in the viral pneumonia group than in the M. pneumonia group with and without virus coinfection. The sex distribution did not differ significantly among the 3 study groups. The procalcitonin level was higher in viral pneumonia and erythrocyte sedimentation rate level was higher in the M. pneumonia group although no significant difference was found in C-reactive protein level between the M. pneumonia and viral pneumonia groups. Conclusion: Clinical features and inflammatory markers between M. pneumonia and viral pneumonia may be useful for the treatment of community-acquired pneumonia. (Allergy Asthma Respir Dis 2018;6:155-160)