From November 1977 through April 1982, a total of 91 patients with glottic cancer (T1N0M0) were treated with the open field technique of 4 MV X ray using bilateral parallel-opposed fields. Total radiation dose administered was 60 Gy in 30 fractions over a 6-week period. Actuarial 5-year disease-free survival rate was 89%. Significant prognostic factors of local control were tumor length (p = 0.021), tumor width (p = 0.001), tumor type (p = 0.004), tumor response to irradiation at 40 Gy (p = 0.000) and 60 Gy (p = 0.000) by chi-square test. Ultimate local control rate by radiation therapy and salvage surgery was 97% and voice preservation rate was 91%.