Several cytokines may play roles in the immunological pathogenesis of mycoplasmal pneumonia caused by Mycoplasma pneumoniae. In this study, we investigated serum cytokine profiles in children with mycoplasmal pneumonia. The serum levels of interleukin (IL)-8, IL-10, and IL-18 were examined using ELISA kits in 34 patients with M. pneumoniae infection (Group 1, 11 with severe mycoplasmal pneumonia; Group 2, 13 with mild mycoplasmal pneumonia; Group 3, 10 with asthma) and 32 age-matched, non-infected controls. The serum levels of IL-8, IL-10, and IL-18 increased significantly in patients with mycoplasmal pneumonia compared with those in controls (P