The volume of a portion of the frontal and occipital lobes was measured in 40 brains in the Yakovlev Collection. In 32 cases the volume of the right frontal lobe was larger than that of the left; in the same number of cases the left occipital lobe was larger than the right (p less than 0.01). The asymmetries existed in fetal brains as early as 20 weeks of gestation. The results confirm observations made with computed tomography and indicate that this nonrandom asymmetrical pattern is an early manifestation of human brain development.