Effectiveness of radiotherapy as a sole treatment modality was analysed in a group of 225 patients with glottic cancer in stage T1 (153 patients) or T2 (72 patients) without metastases in regional neck lymph nodes. All patients were irradiated with gamma 60Co or 10 MeV photons 5 times per week conventional treatment with the dose of 2.0-2.5 Gy per fraction. The total dose was in the range of 60-70 Gy given in overall treatment time of 30-61 days. 3-year local control rate was 88% for T1 patients and 54% for T2. In group T1 total dose of 65-70 Gy correlated with a high, 94-100%, local rate whereas in group T2 for the same range of total dose, extension of overall treatment time beyond 45 days caused significant decrease in local tumour control of about 3% for each one day of treatment protraction. Moreover, the Hb level was found to be a significant prognostic factor and its value below 12 g/dl correlated with remarkably lower local control of glottic cancer of about 30% comparing with patients with Hb level above 12 g/dl.