The purpose of this study was to investigate the effects of 2450 MHz and 9450 MHz microwaves an the phagocytic activity of rat macrophages in rats without treatment and treated with exercise, vitamins C and E, dexamethasone, and both dexamethasone and vitamin C. Alveolar and peritoneal exudates from Swiss albino rats were exposed to microwaves for 1, 5, and 10 secs. The results were analyzed with the Mann-Whitney U test. In the group exposed to 2450-MHz microwaves, altered phagocytic activity of macrophages was found to be significant for each exosure period (p <.05). In the groups that were additionally subjected to vitamin C, vitamin E, and combined treatment with vitamin C and dexamethasone, phagocytic activities were found to be changed for only 10 s (p <.05), 1 and 5 s (p <.05), and 1 s (p <.05), exposure, respectively. In the groups exposed to 9450-MHz microwaves alone and microwaves plus vitamin E, altered phagocytic activities were found to be significant for each exposure period (p <.05) and for only 1 s exposure (p <.05), respectively. The differences between pre- and postexposure temperatures were also found to be significant (p < .05).