The horned guan (Oreophasis derbianus) is an endangered species with small and seriously fragmented wild populations. Breeding efforts during the last decade have maintained a slowly increasing captive population with the potential to play an important role in the recovery of the species. Clinical hematology and biochemistries are powerful tools to diagnose and monitor diseases in captive birds. Therefore, establishing hematologic and plasma biochemistry reference values will improve the medical management of this species. This study determines the reference values for 9 hematologic and 15 plasma biochemical variables for 27 male and 12 female, apparently healthy, captive horned guans from three institutions. Differences related to age, sex, and husbandry were identified but were usually small and clinically insignificant. These results should improve veterinary care of captive individuals of this species and provide comparative data for other species of cracids.