Baseline haematology, blood chemistry and acute phase protein parameters have not previously been published for free-ranging eastern grey kangaroos (Macropus giganteus). Eight eastern grey kangaroos, including three adult males, three adult females and two subadult males from two different populations, were examined. Assays assessed the antibacterial activity of kangaroo serum against one Gram-positive and three Gram-negative bacteria. The kangaroo serum had a strong antibacterial response to Klebsiella pneumoniae, and moderate responses to Escherichia coli and Staphylococcus aureus. The presence and level of acute phase proteins, haptoglobin and serum amyloid A in kangaroos was investigated. Haptoglobin and serum amyloid A were present in kangaroo serum, but only haptoglobin was elevated in a kangaroo with capture myopathy and necrotic wounds. The findings of this study provide preliminary data on health parameters of free-ranging eastern grey kangaroos. These parameters can be used to assist in assessing health in free-ranging populations.