Four hundred and fifty pairs of adrenals were studied from human fetuses ranging in age from 15 to 27 weeks of gestation (menstrual age). They were collected from spontaneous and medical abortions. The adrenal weight increased from 0.2 to 1.5 g during the second trimester. The left adrenal was significantly heavier than the right for the same gestational age. The length (L₁), the height (L₂) and the thickness (L₃) of the adrenals were measured. The index of length (L₁ X L₂ X L₃) correlated well with the fetal age, except for the Potter Syndrome in which it was decreased. This index could be a useful indicator for ultrasonographic and pathologic studies of the fetal adrenal gland. The cells of the fetal cortex contained lipid droplets during the first weeks of the mid-trimester, and this storage progressively decreased after 20–21 weeks. The fatty transformation that is used as an indicator of the mode of death of stillborn infants cannot be applied to abortions during the second trimester. In a few instances, hypoxia was associated with adrenal hypertrophy.