The effect of electron-beam intraoperative radiotherapy (IORT) with radiosensitizer sanazole (drug AK-2123) on the functional activity of neutrophils and monocytes in patients with gastric cancer was studied with the use of luminol-amplified chemiluminescence. Sanazole was administered intravenously in a dose of 1.2 g/m2, 30 min before IORT. After resection of the tumor a single dose of 10 Gy was given to the field of regional lymph collectors and the bed of the removed tumor applying a small-size betatron MIB-6E. Cells were separated and chemiluminescence was estimated on the 1-st day before and on the 3-d day and 2-d week after IORT with sanazole. Insignificant effect on the zymosan- or phorbol-12 -myristate-13-acetate (PMA)-stimulated chemiluminescence was observed in this group, although there was found a considerable increase of chemiluminescence of neutrophils in response to zymosan and PMA in 5 from 8 patients, and chemiluminescence of monocytes--in 3 from 8 patients. Correlation between individual indices of zymosan- and PMA-stimulated chemiluminescence of neutrophils before IORT with sanazole was not high, r = 0.71, but it increased significantly to r = 0.91 on the 3-d day and to r = 0.96 on 2-d week after treatment. Correlation between individual indices of stimulated chemiluminescence of monocytes before IORT with sanazole was r = 0.90, and increased to r = 0.99 on the 3-d day and to r = 0.96 on the 2-d week after treatment. So, it is indicative of a correcting effect of the combined treatment including IORT with sanazole administration on the functional activity of neutrophils and monocytes, and the absence of functional disturbances of these cells.