The aim of the study was to examine the effects of bronchitis on elastin-derived peptides (EP) and antielastin antibodies (AEAb) in serum. Using an ELISA technique, these parameters were assessed in children aged 6 months to 15 years: 36 had recurrent bronchitis (RB), 34 had obstructive bronchitis (OB) and 37 were healthy children (C). A comparison of the levels of the investigated compounds in the acute phase (I) and stage without signs of diseases (II) was studied. The EP data show non-significant changes in the RB and OB groups in comparison with group C. Children with OB had significantly lower levels of AEAb in IgA, IgG and IgM class antibodies, while those with RB in the IgG class in comparison with group C in both examinations. In examination 1, AEAb in IgA and IgM classes were significantly lower in children with OB than with RB.