The objective of this study was to assess the diagnostic usefulness of plasma levels of polymorphonuclear neutrophil elastase-alpha 1-proteinase inhibitor complex (E-alpha 1PI) in children with bronchitis. One hundred and seven children aged 6 months to 15 years were studied: 36 with recurrent bronchitis (RB), 34 suffering from obstructive bronchitis (OB) and 37 disease free-control group (C). Systemic inflammatory response by ESR, total leukocyte (L), polymorphonuclear count (PMN), alpha 1-proteinase inhibitor (alpha 1PI) and C-reactive protein (CRP) in the blood was monitored simultaneously. A comparison of the levels of the investigated indicators in the acute phase (I) and in the stage without signs of diseases (II) was carried out. Upon examination 1, about 90% of the patients in both groups had mean levels of E-alpha 1PI significantly elevated (p < 0.001) over the control group. There was no significant correlation between the E-alpha 1PI concentration and other analyzed indicators of inflammation. These results show that E-alpha 1PI may serve as a sensitive indicator for granulocyte activation during the acute course of the disease, even in neutropenia.