The relationship between serum alpha-tocopherol level and many of its possible determinants was studied in 1,373 cancer-free Finnish men and women age 40-79 years. Dietary data were available from a subsample of 301 persons. The mean alpha-tocopherol level in the serum samples stored at -20 degrees C was 8.6 mg/liter among men and 10.5 mg/liter among women. Intake of margarine, vegetable oils, and green vegetables predicted the serum level of alpha-tocopherol. Altogether six food groups accounted for about 10% of the variation. The levels also varied with age, geographical area, type of population, occupation, socioeconomic status, and marital status. They were positively correlated with serum cholesterol and serum vitamin A in both sexes, and with body mass index and serum selenium in men. Altogether these variables accounted for over 40% of the variation in alpha-tocopherol levels. The level of serum alpha-tocopherol, which is associated with the dietary intake of vitamin E, is dependent upon living conditions.