Eighty-one patients with preinvasive carcinoma of the vocal cord, seen over a thirteen year period, were reviewed histologically and analyzed for response to treatment. Sixty-seven cases were clinically T1 and fourteen cases T2 (by virtue of extension of disease beyond the vocal cord). All patients had mobile cords. Histological criteria for in situ carcinoma and the spectrum of microscopic patterns are presented. Sixty-nine patients were treated by external beam radiotherapy--the remainder by a variety of surgical procedures. Five and ten year actuarial, recurrence-free rates 83% and 75%, respectively for the group treated by irradiation. No difference in local control was observed when analyzed for: 1) dose response, 2) initial extent of disease, 3) treatment plan, or 4) histologic diagnosis. Analysis of failures reveals that 15/17 patients with local failure were salvaged, eleven of these patients requiring laryngectomy. Time to appearance of recurrence ranged from seven to one hundred and seven months.