To determine reference values for plasma alpha-tocopherol concentrations in falcons and to investigate a possible dietary impact, 29 falcons were randomly selected from a collection of 500 captive breeding falcons fed with 4-week-old chicks. Blood samples collected from each falcon were analyzed for plasma alpha-tocopherol concentrations. Reference values were 16.7-46.1 mg/L with a mean plasma alpha-tocopherol concentration of 27.5 +/- 8.7 mg/L. A group of 5 gyr-saker falcon hybrids (Falco rusticolus x Falco cherrug) were fed 1-day-old chicks for 4 weeks; the resultant mean plasma alpha-tocopherol concentration was 34.9 +/- 5.6 mg/L. When the diet was changed to turkey breast meat for 4 weeks, the mean plasma alpha-tocopherol concentration decreased significantly to 13.1 +/- 2.6 mg/L. Results appeared to support the influence of diet on plasma alpha-tocopherol concentrations in falcons.