1. Torpor is a state of reduced metabolism that allows animals to conserve energy during periods of limited resources. Critical physiological processes, including the immune function are downregulated during torpor - a phenomenon that remains relatively understudied in bats, especially in the southern hemisphere. 2. This study examines the effects of torpor on the immune system of the eastern bent-winged bat (Miniopterus orianae oceanensis), an Australian cave-roosting species. We captured 52 ba