Abstract We collected blood samples (n = 49) from 43 Andean Bears (Tremarctos ornatus) in Ecuador between September 1995 and May 2006 and analyzed them for 11 serum biochemical and 13 hematological parameters. Results were grouped and compared according to the bears' life condition (captive or free-ranging), sex, age, and body mass. Free-ranging bears had higher serum glucose and monocyte levels than captive bears, but slightly lower mean cellular hemoglobin concentrations. Male bears had higher serum protein levels than female bears. Adult bears showed higher levels of cholesterol, hematocrit, and hemoglobin than sub-adult bears. In contrast, alkaline phosphatase and phosphorous levels were higher in sub-adult bears. Bears with a body mass >80 kg had higher levels of serum proteins and blood urea nitrogen than lighter-weight bears. Plasma triglyceride levels observed in this study were very high in relation to those reported for other bear species. Alkaline phosphatase levels were also high in comparis...