The mean plasma level of α-to-copherol (vitamin E) measured in 31 free-ranging black rhinoceros (Diceros bicornis) was significantly higher (P < 0.001) than that in 11 captive animals (x̄ ± SE = 0.77 ± 0.05 and 0.18 ± 0.03 μg/ml, respectively). Vitamin E status may influence the health of captive black rhinoceros; in particular, it may be linked to hemolytic anemia commonly observed in these animals in captivity.