Background: The question of whether low levels of non-ionizing radiations such as the radiofrequency electromagnetic fields (RF-EMF) can induce the same positive immune responses remains unanswered. This study aimed to investigate the effects of non-ionizing RF-EMF on some parameters of the immune system in an animal model following infection with Salmonella Typhimurium and Klebsiella pneumoniae. Materials and Methods: Male BALB/c mice were exposed to RF-EMFs generated by a common GSM mobile phone for 3 days. Animals were infected with K. pneumonia or S. Typhimurium on the 4^th day. On the7^th day after injection, blood samples were collected by cardiac puncture. The specific antibodies against bacteria were determined by agglutination method and serum levels of the cytokines were measured using the ELISA method. Moreover, the leukocytes count was measured using a cell counter. Results: The levels of specific antibodies against bacteria were higher in non-irradiated mice compared to irradiated mice. There were no significant differences between the irradiated and non-irradiated mice regarding the total blood leukocyte count. The mean serum levels of IFN-γ and IL-17 after infection with K. pneumoniae were significantly higher in the irradiated mice (p<0.001). Conclusions: Low levels of RF-EMF can stimulate the immune responses in the mice pre-exposed to RF-EMF. This study provides further evidence supporting that exposure to certain levels of RF-EMF can stimulate the immune system. These adaptive responses may be applied to cope with the increased susceptibility of the astronauts to infections during a deep space mission.