Asthmatic attacks can be triggered by allergens, irritans, infections and emotional factors. This study was set up to investigate whether Chlamydia pneumoniae infections play a role in attacks of asthma or not. Eighty children of 5-15 years of age were taken into the study, 50 asthmatic and 30 controls, considering the fact that attacks are the most frequent in this age group. Chlamydia pneumoniae IgM and IgG antibodies were investigated in sera by enzyme immuno-assay (ELISA) and microimmune fluorescence test (MIF) methods. IgM and IgG were found positive in nine and six cases, respectively, by ELISA while it was seven and two by MIF method. In the control group, IgM and IgG were positive in three and two cases, respectively, by ELISA. These cases were also found positive for the related antibodies by MIF method. In conclusion, no significant relation was found between C. pneumoniae infections and bronchial asthma attacks in children.