The cricoid is the only complete cartilaginous ring in the skeleton of the airway. This laryngeal cartilage is thought to function as essential support for the airway lumen. Interruption of the circular structure has often been held responsible for the development of subglottic stenosis. The treatment of acquired subglottic stenosis in infants and children is a challenging problem. A wide variety of both conservative and surgical methods have been recommended. Some authors advocate an anterior midline cricoid split as the method of treatment in children with subglottic stenosis. To date it has not been possible to cure all patients. The reasons for failure of therapy are still not well understood. Therefore, it is necessary to investigate systematically the factors which can give rise to poor results. This experimental study focused on the effects caused by interruption of the circular structure of the cricoid cartilage on the subglottic lumen and the histologic changes seen after interruption of the cricoid ring. The results obtained were as follows : 1) Splitting the cricoid cartilage and adjacent soft tissue induced specific deformities. 2) Anterior splitting of the cricoid cartilage caused a widening of the interrupted surface and invagination of regenerated mucosa into the lumen. 3) Bilateral splitting of the circular structure of the cricoid ring also caused the straightening of the anterior segment and the U-shaped deformity of the posterior segment. 4) The spaces between the cutting surface of the cricoid cartilage were histologically connected with muscle fiber and fibrous tissues, and there was no evidence of the regeneration of the new cartilage. 5) Splitting of the anterior midline of cricoid cartilage with posterior cricoid damages caused the development of narrowing of subglottic airway by mucosal thickening and a large amount of muscle fibers. 6) No major changes on normally shaped and sized subglottic airway lumen were observed as long as the soft tissue lining of the airway was preserved.