The glottis consists of two parts : The intermembranous portion or the anterior glottis, and the posterior glottis. The posterior glottis has been described by various inappropriate terms such as posterior commissure and interarytenoid region. The structure surrounding the posterior glottis consists of three portions ; The cartilaginous portion of the vocal fold, the lateral wall of the posterior glottis, and the posterior wall of the glottis. The posterior glottis may be a very rare site for primary squamous cell carcinoma of the larynx because of its embriologic and histologic differences from the anterior glottis. Recently we have experienced a case of a 81-year-old woman who had been presented with throat discomfort and voice change for 10months. She had the smoking history of 40 pack-year. The physical examination revealed poorly demarcated, papillary, whitish-pink colored mass on the posterior glottis. The vocal cord mobility was not affected. Biopsy under the suspension larygoscope showed moderately differentiated squamous cell carcinoma. No regional and distant metastasis was found. She was irradiated with 7000cGy over 7 weeks at a daily dose of 200cGy. No evidence of recurrence was found by the fifteenth month following radiation therapy. We report this case with a review of literature.