This study is concerned with differences between breast-fed and bottle-fed infants in plasma and red blood cell (RBC)-levels and pattern of tocopherol analogues. Tocopherol levels were determined by High-Performance Liquid Chromatography (HPLC). The results were as follows: 1. In breast-fed infants the plasma contained larger amounts of the alpha and smaller amounts of the gamma form of tocopherol than in bottle-fed infants but the RBC contained the alpha form alone. 2. In the bottle-fed infants the plasma contained the alpha, gamma, and delta forms, but the RBC contained the alpha form alone. 3. In bottle-fed infants plasma alpha-tocopherol levels did not differ significantly from those in breast-fed infants but RBC alpha-tocopherol levels were far lower in the former. In contrast, plasma gammatocopherol levels were significantly higher in bottle-fed infants. 4. Cord blood plasma contained only the alpha and gamma forms with the patterns similar to those in adults. The delta form appeared in the plasma of bottle-fed neonates as early as 3 or 4 days after birth. 5. The transitional-form human milk obtained on the 5th postpartum day contained the alpha and gamma forms alone and resembled adult plasma. On the other hand, commercially available formulas contained all four forms, with the gamma form the highest, alpha and delta forms moderate, and only slight beta.