Fifty-one laryngectomy specimens were histopathologically studied in serial sections. The incidence of thyroid cartilage invasion was 10% in supraglottic, 48% in glottic, and 67% in subglottic carcinomas. The incidence of cricoid cartilage invasion was 0% in supraglottic, 22% in glottic, and 33% in subglottic carcinomas. The sites of cartilage invasion were the anterior commissure portion and an ossified lower portion of the thyroid cartilage, and an ossified upper portion of the cricoid cartilage. Fixation of the vocal fold in glottic carcinoma was accounted for by carcinomatous invasion into three-fourths or more of the thyroarytenoid muscle. Impairment of the vocal fold movement was accounted for by carcinomatous invasion into three-fourths or less of the thyroarytenoid muscle. Fixation of the vocal fold in supraglottic carcinomas was accounted for by a massive carcinomatous invasion around the upper aspect of the arytenoid cartilage.