A study was made of the results of therapy of 66 patients with maxillary cancer, of them 31 (a control group) received routine therapy by a method of summary focal dose (SFD) fractionation--60-70 Gy. In the study group (35 patients) treatment was started with large fractions at a dose of 5 Gy 2 times a week up to SFD of 20 Gy using metronidazole 2.5-3 h before each of the first 4 large fractions and continued using a course with SFD up to 52 Gy by common fractionation. Staged assessment of the results of radiotherapy was done when the summary dose reached 40 Gy in the control group and 32 Gy in the study group. Complete regression of a tumor or a decrease in its volume by more than 50% at these doses were noted in 13 (41.9%) patients of the control group and in 23 (65.7%) patients of the study group. After combined treatment of a slightly decreased tumor preirradiated in a summary dose of 40 Gy and 32 Gy the 3-year recurrence-free survival was noted in 72.2% (13 patients) in the control group and in 91.7% (11 patients) in the study group. The results obtained are indicative of a marked radiosensitizing effect of metronidazole in radical radiation and combined radiation therapy of maxillary cancer improving long-term results.