Recent studies show acute stress-induced immunomodulation, particularly emphasizing that physiological increases in endogenous glucocorticoid levels have immunostimulatory effects. Although immunosuppressive effects have also been described, the difference between enhancing or suppressing the immune response seems to be mediated by the duration and intensity of the stressor, and the immune component analyzed. We aimed to understand how acute increased glucocorticoid levels of different intensities, promoted by two corticosterone (CORT) doses (1 and 10ug) using the transdermal application (TA), affect CORT and testosterone (T) plasma levels and immune parameters (plasma bacterial killing ability (BKA), and phagocytosis of peritoneal leukocytes (PP)] in toads (Rhinella icterica). Toads were bled one hour after TA (CORT or vehicle), and subsequently received an intraperitoneal injection of zymosan-CFSE. One hour following the zymosan-CFSE injection, toads were euthanized to collect the peritoneal lavage fluid. CORT TA increased plasma CORT levels with different intensities: three times for 1ug and fourteen times for 10ug, although there was no effect of any dose on T levels and BKA. Interestingly, both CORT doses promoted immunosuppression, decreasing phagocytosis in 60% for toads receiving the dose of 1ug and 40% for those receiving 10ug. Thus, CORT immunomodulatory effect on amphibians appears to be quite complex, and not just dependent on the intensity of CORT increase. Moreover, the immunomodulatory effect varied according to the immune component analyzed (complement proteins vs. cellular response).