Brains from 74 children aged from birth to 12 years were used to study fibroarchitectonic characteristics in topographically and functional diverse cortical zones (the temporal-parietal-occipital subregion, occipital, precentral, postcentral, and frontal areas) of the cerebral cortex; children aged up to 12 months were studied on the basis of one-month age intervals. Studies were performed by computer analysis of optical images on frontal sections stained with Nissl cresyl violet and silver nitrate impregnation by the modified Peters method. Data on the rate of increase in the thickness of radial bundles of fibers, the distances between bundles, and the age dynamics of the ratios of the specific volumes of neurons and fibers in fields 3, 4p, 6op, 17, 19, 37ac, 44, and 32/10 were obtained. These measurements showed that age-related transformation of fibroarchitectonics in fields of the sensorimotor, somatosensory, occipital, temporal-parietal-occipital, and frontal areas occurred at different times and with different intensities; the most significant changes were seen in the first 2-3 years of life, with changes continuing at a less intense level to age 9-12 years.