Health screening of animals before translocation is important to minimize the risk of pathogen transmission between sites and species. Reintroduction has been incorporated into management of the endangered western ringtail possum ( Pseudocheirus occidentalis ) to mitigate for habitat loss within the species' core range in southwestern Australia. Between November 2005 and March 2008 we screened 47 wild and 24 captive P. occidentalis and 68 sympatric common brushtail possums ( Trichosurus vulpecula hypoleucus ) for infectious diseases that might compromise possum survival or fecundity at translocation sites. We found no evidence that infectious disease limits translocation success, and neither possum species showed evidence of infection with Salmonella spp., Toxoplasma gondii , Leptospira... spp., or Chlamydophila spp. Antigen of Cryptococcus gattii was detected in one T. v. hypoleucus but was not of pathologic significance. Hematologic and serum biochemical reference ranges were determined for 81 wild and 24 captive P. occidentalis . Site differences were identified for red blood cell count, hemoglobin, albumin, urea, and globulin, suggesting that habitat quality or nutrient intake may vary among sites. Differences between wild and captive values were found for several parameters. These data are useful for health evaluations of injured P. occidentalis and the future monitoring of wild populations.