A rapid and convenient automated procedure for the determination of alpha-tocopherol is described. As little as 0.3 ml of serum or plasma can be used at a sample rate of 20 per hour and carry-over is negligible. Within-batch precision was 4.71% at 5.0 mg alpha-tocopherol per 1, and 3.68% at 20 mg/l, compared with a between-batch precision of 6.98% at 10 mg/l. Using this procedure alpha-tocopherol has been found to be distributed in a log-normal manner and on that basis the range of values for 80 haematologically normal subjects was calculated to be 4.0 to 16.0 mg/l. In pregnancy the alpha-tocopherol was elevated, ranging from 6.7 to 24.0 mg/l. During the first year of life normal infants ranged from 2.0 to 16.0 mg/l which was higher than a small group with various disorders whose values ranged from 1.2 to 8.3 mg/l. The cord blood level was approximately one-fifth of the maternal level.