Vitamin E (alpha- and gamma-tocopherol) and total lipid concentrations were determined in the serum of 451 healthy human male and female subjects ranging in age from 19 to 70 years. Mean serum alpha-tocopherol concentration (microgram/ml) was 8.82 +/−2.84 (SD) and gamma-tocopherol concentration was 1.35 +/−0.70. The concentration of alpha-tocopherol increased significantly with age, as well as with total lipid; gamma-tocopherol concentration remained unchanged with age. The data also indicated that subjects with higher serum alpha-tocopherol had lower gamma-tocopherol levels and vice versa for subjects with higher gamma levels. A close interrelationship and competition appeared to exist between these two vitamers.