AbstractHuman vision has striking radial asymmetries, with performance on many tasks varying sharply with stimulus polar angle. Performance is better on the horizontal than vertical meridian, and on the lower than upper vertical meridian, and these asymmetries decrease gradually with deviation from the vertical meridian. Here we report cortical magnification at a fine angular resolution around the visual field. This precision enables comparisons between cortical magnification and behavior, between cortical magnification and retinal cell densities, and between cortical magnification in twin pairs. We show that cortical magnification in human primary visual cortex, measured in 181 subjects, varies around the visual field, with a pattern similar to behavior. We find that these cortical asymmetries are larger than those found in the retina, and that they are correlated between monozygotic twin pairs. These novel findings indicate a tight link between cortical topography and behavior, and suggest that visual field asymmetries are, at least in part, heritable.