Immunological examinations of 40 children with papillomatosis and chronic cicatricial stenosis of the larynx included measurements of circulating immune complexes (CIC) and lysozyme in the saliva and serum as well as complement activity in serum. The examinations were performed regularly during treatment. It was found that immunobiological factors played an important part in the pathogenesis of papillomatosis and cicatricial stenosis of the larynx in children. It was shown that CIC and lysozyme concentrations in the saliva and serum as well as complement activity in serum increased. In the course of treatment all the groups displayed an increase of lysozyme in the saliva; patients with papillomatosis showed a decrease of the CIC concentration and those with cicatricial stenosis a decline of complement activity in serum. Involvement of the autoimmune component in the pathogenesis of the above diseases is discussed. Applicability of the results for controlling the therapeutic efficacy and predicting the outcome of diseases is considered.